I am not an expert on DAZ Studio but when I sought on the Internet and in F95, I did not find anything like this - if someone wants to correct me (and the mods to cancel the post), or suggest improvements, feel free.
I found some instructions passing through Genesis or G2F, and generic suggestion that one could have gone through genesis or to G2, then from G2, to G3F, and eventually moving to G8F, creating a character at every step.
But none of the instruction I found, all old, worked fully as indicated, whether saying with GenX you could drag and drop the inj and 4.2 in it and it will do it, or referring to the transfer utility (which seems more focused on clothing).
Notice I did it for V4 to G3F, but it should work in the same identical way to bring a character based on M4 to G3M (adapting what needed).
I think all the "tools" I used can be found between F95 and 3d-load, although I admit I cannot guarantee it, because I alos bought lots of stuff over time.
Tools used: V4.2 (plus the morphs++, Aiko 4, or whatever your V4 character requires), "Legacy UVs for G3 - V4", Gen X + GenX2 Add-on (to have the support for G3F)
Optional: Iray converter for generation 4, or, if you want to use the "Victoria 4 Skins batch converter to Genesis 2 Female(s)" (but I don't know it if creates directly the DUF files you need at the 12th step, I guess so), then you need the "Legacy UVs for G3 - G2F"
Note about step 6
In the same disk where I have the DAZ default Library used by DIM , I also put another folder where I have other stuff (e.g. converted), and I added also that folder to DAZ.
Basically , I have on a disk a path for DAZ assets called DazLibrary, which branches in a folder for DIM-installed stuff, one for MyDazConnect (I don't use it, but it's needed), etc., including an "Others", which underneath as a Runtime folder, etc.
Simply install everything, then:
1) Install your character (I personally like to use the content package assistant and package them for DIM, but it's up to choice);
2) Load V4.2 (when asked about the morphs, I take on board everything, so I don't have to bother to check the prerequisites for the specific character);
3) Inject the morphs for your character in the V4.2, and then apply the materials;
4) Optional step, use the "Iray converter for Generation 4" , it is not strictly needed, up to taste (I renedered directy the V42 using Iray without it, and it did render quit well in a couple of cases, but it was a bit better with the Iray converter, even if I used just the basic without working on the glossiness, and in one case, without it it was too shiny)
5) Save as "material preset" somewhere you want (File, Save As, Material(s) Preset) - if there are various options for the materials (e.g. eyes colors, tattoos) and you want to have them all ready for use, you need to do it for each of the sets.
If you plan to add up gen add-ons, and plan to use the G3F "default" genitals, it is better to use a materials set that does not include the genital area, the "copy the torso surface to the genitals" approach works for some model, but then you end up with the image of genital from the material superimposed on the genital, it's weird;
6) Export as Poser figure, .cr2 format, and choose to export the binary morph file (otherwise, effectively nothing will be saved
) - in theory you can use any folder by , in practice, in the "base path" you should use a path that ends with "Runtime" and is configured in DAZ as Poser contents folder, e.g. disk:\DazLibrary\Others\Runtime\ , in my case I like to create a subfolder for each character under that path, adding a Libraries\Characters\whatever_character folder
7) Load your G3F basic female (note, some addons like dForce breast are ok) - not strictly needed, but it can be useful in 10);
8) Launch GenX, click on "load figure", go find your cr2 file and load it (it will remember the last folder used, so, it should be just a couple of clicks, after the first time);
9) Select the morphs to transfer for each part listed (BODY, rEye, hips, etc.) - if you click on the arrow aside e.g. BODY, it opens the list - I prefer to tell it to transfer conditional morphs, and to create a single morph (if you have too many morphs affecting characters, DAZ Studio will crawl, confirmed from practice, and even from DAZ support).
Click on "transfer", then indicate a name that will become the name of the new morph for G3 (so, make sure it is something you can remember in future).
It is in theory possible to transfer all the morph, but I suspect the processing time will become much longer, and the final single morph file will be bigger
Tip1 You can do right click in the list of the morphs, choose "all", then "All: Transfer for non-zero values" and get the same result as selecting manually the morphs
10) Go in the parameters for your G3F base figure, and find the newly created morph, and put the value of the morph to 1 - you may have to reopen DAZ to see it , but in general, it is not necessary - as a tip (the software will tell you), you can find the morphs under "actor","Generation X" in the parameters panel.
11) launch the "prepare G3" of the "Legacy UVs" product, it will select the G3 and all his grafts automatically
12) Without deselecting G3 and the grafts, merge (from file menu, choose merge, then find the file) the duf file with the material settings you saved in step 5) - it is the reason for step 5, you must use a .duf file, and most of the V4 characters I found or bought, do not have .duf files, even when they have materials for DAZ.
13) Click on the "apply V4 UVs" of the Legacy UVs product (if you added the toolbar, is in the toolbar, otherwise, in the product) - in theory according to the readme, it is not always needed , but I have not yet found one character when I did not need to do also this step - also be aware characters may require a small adjustments of the eyes position (not all, though).
14) Optional add up genitals, change the height, or do whatever other morph you want to do (e.g. the correct height), be aware that you may need to use different genitals depending on the model
15) Remember to save your "new" character
About the saving, I admit I have been saving just as a scene subset, but if you want to be sure that your "new" converted character will work in case you need to go to another computer or reinstall yours and don't want (or cannot) reinstall everything you have, remember to save it as a full character.
Notice if you are only interested in using poses from G3F/G8F with V4(.2) characters, there is some free scripts that allow you to copy poses from G8F to V4 (load G8F, load V42, use the script, it transfers it) and even viceversa, and from a little test, they work nicely (though G8F to V42 seems to work well out of the box, the reverse may need small adjustments in some joints, due to the differences between models).
If you combine that, with the scripts that allow to use poses made for G3 on G8, in theory it can give your V4(.2) character access also to all the poses for G3 and G8.
If you ask why doing it, probably from one side means you don't need it.
Anyway, the answer is simply that there are some nice characters out there for V4, which can be used on the V4.2 with DAZ Studio, but do not have the same character with G3 or G8, and some celebrities for which either there is no character, or the visual correspondence of the old V4 character is better - but at the same time, there are lot of nice clothing, poses, morphs to fine tune the character, add-ons and accessories around for G3F and G8F (which can be used also on G3 with converter/clones).
Hope it is useful, have fun !
I found some instructions passing through Genesis or G2F, and generic suggestion that one could have gone through genesis or to G2, then from G2, to G3F, and eventually moving to G8F, creating a character at every step.
But none of the instruction I found, all old, worked fully as indicated, whether saying with GenX you could drag and drop the inj and 4.2 in it and it will do it, or referring to the transfer utility (which seems more focused on clothing).
Notice I did it for V4 to G3F, but it should work in the same identical way to bring a character based on M4 to G3M (adapting what needed).
I think all the "tools" I used can be found between F95 and 3d-load, although I admit I cannot guarantee it, because I alos bought lots of stuff over time.
Tools used: V4.2 (plus the morphs++, Aiko 4, or whatever your V4 character requires), "Legacy UVs for G3 - V4", Gen X + GenX2 Add-on (to have the support for G3F)
Optional: Iray converter for generation 4, or, if you want to use the "Victoria 4 Skins batch converter to Genesis 2 Female(s)" (but I don't know it if creates directly the DUF files you need at the 12th step, I guess so), then you need the "Legacy UVs for G3 - G2F"
Note about step 6
In the same disk where I have the DAZ default Library used by DIM , I also put another folder where I have other stuff (e.g. converted), and I added also that folder to DAZ.
Basically , I have on a disk a path for DAZ assets called DazLibrary, which branches in a folder for DIM-installed stuff, one for MyDazConnect (I don't use it, but it's needed), etc., including an "Others", which underneath as a Runtime folder, etc.
Simply install everything, then:
1) Install your character (I personally like to use the content package assistant and package them for DIM, but it's up to choice);
2) Load V4.2 (when asked about the morphs, I take on board everything, so I don't have to bother to check the prerequisites for the specific character);
3) Inject the morphs for your character in the V4.2, and then apply the materials;
4) Optional step, use the "Iray converter for Generation 4" , it is not strictly needed, up to taste (I renedered directy the V42 using Iray without it, and it did render quit well in a couple of cases, but it was a bit better with the Iray converter, even if I used just the basic without working on the glossiness, and in one case, without it it was too shiny)
5) Save as "material preset" somewhere you want (File, Save As, Material(s) Preset) - if there are various options for the materials (e.g. eyes colors, tattoos) and you want to have them all ready for use, you need to do it for each of the sets.
If you plan to add up gen add-ons, and plan to use the G3F "default" genitals, it is better to use a materials set that does not include the genital area, the "copy the torso surface to the genitals" approach works for some model, but then you end up with the image of genital from the material superimposed on the genital, it's weird;
6) Export as Poser figure, .cr2 format, and choose to export the binary morph file (otherwise, effectively nothing will be saved
) - in theory you can use any folder by , in practice, in the "base path" you should use a path that ends with "Runtime" and is configured in DAZ as Poser contents folder, e.g. disk:\DazLibrary\Others\Runtime\ , in my case I like to create a subfolder for each character under that path, adding a Libraries\Characters\whatever_character folder7) Load your G3F basic female (note, some addons like dForce breast are ok) - not strictly needed, but it can be useful in 10);
8) Launch GenX, click on "load figure", go find your cr2 file and load it (it will remember the last folder used, so, it should be just a couple of clicks, after the first time);
9) Select the morphs to transfer for each part listed (BODY, rEye, hips, etc.) - if you click on the arrow aside e.g. BODY, it opens the list - I prefer to tell it to transfer conditional morphs, and to create a single morph (if you have too many morphs affecting characters, DAZ Studio will crawl, confirmed from practice, and even from DAZ support).
Click on "transfer", then indicate a name that will become the name of the new morph for G3 (so, make sure it is something you can remember in future).
It is in theory possible to transfer all the morph, but I suspect the processing time will become much longer, and the final single morph file will be bigger
Tip1 You can do right click in the list of the morphs, choose "all", then "All: Transfer for non-zero values" and get the same result as selecting manually the morphs
10) Go in the parameters for your G3F base figure, and find the newly created morph, and put the value of the morph to 1 - you may have to reopen DAZ to see it , but in general, it is not necessary - as a tip (the software will tell you), you can find the morphs under "actor","Generation X" in the parameters panel.
11) launch the "prepare G3" of the "Legacy UVs" product, it will select the G3 and all his grafts automatically
12) Without deselecting G3 and the grafts, merge (from file menu, choose merge, then find the file) the duf file with the material settings you saved in step 5) - it is the reason for step 5, you must use a .duf file, and most of the V4 characters I found or bought, do not have .duf files, even when they have materials for DAZ.
13) Click on the "apply V4 UVs" of the Legacy UVs product (if you added the toolbar, is in the toolbar, otherwise, in the product) - in theory according to the readme, it is not always needed , but I have not yet found one character when I did not need to do also this step - also be aware characters may require a small adjustments of the eyes position (not all, though).
14) Optional add up genitals, change the height, or do whatever other morph you want to do (e.g. the correct height), be aware that you may need to use different genitals depending on the model
15) Remember to save your "new" character
About the saving, I admit I have been saving just as a scene subset, but if you want to be sure that your "new" converted character will work in case you need to go to another computer or reinstall yours and don't want (or cannot) reinstall everything you have, remember to save it as a full character.
Notice if you are only interested in using poses from G3F/G8F with V4(.2) characters, there is some free scripts that allow you to copy poses from G8F to V4 (load G8F, load V42, use the script, it transfers it) and even viceversa, and from a little test, they work nicely (though G8F to V42 seems to work well out of the box, the reverse may need small adjustments in some joints, due to the differences between models).
If you combine that, with the scripts that allow to use poses made for G3 on G8, in theory it can give your V4(.2) character access also to all the poses for G3 and G8.
If you ask why doing it, probably from one side means you don't need it.
Anyway, the answer is simply that there are some nice characters out there for V4, which can be used on the V4.2 with DAZ Studio, but do not have the same character with G3 or G8, and some celebrities for which either there is no character, or the visual correspondence of the old V4 character is better - but at the same time, there are lot of nice clothing, poses, morphs to fine tune the character, add-ons and accessories around for G3F and G8F (which can be used also on G3 with converter/clones).
Hope it is useful, have fun !