Here is how I have been MANUALLY converting clothing items to var, Outside of VaM. If you are repacking a look/scene, there are a few more steps.
Remember to copy and paste, or make a backup of the file you are going to edit.
All images I posted here are in order from 001 to 007.
First I COPY and PASTE any working clothing .var by the same creator to DESKTOP. I then right click, 7-Zip and extract to "var name here"\ with 7-Zip.
*I then go to Custom/Clothing/Female/CREATOR NAME/ and delete "ITEM NAME" folder and drag and drop the new clothing folder I am going to use*.
I then open and edit the meta.json with notepad or notepad++.
In the meta.json change the "package name" to what the name of the item is.
In the meta.json change the "description" to describe the new item.
In the meta.json change the "content list" to point to the item after making sure the link leads to the correct files.
Save meta.json and exit.
I am using Jakuubz as a reference, since these are the clothing items I just finished converting. The link should look like this.
Custom/Clothing/Female/CREATORS NAME/ITEM NAME
See image 001.jpg
For CREATORS NAME, I put Jakuubz, for the ITEM NAME, I put Booty_Shorts. *Don't forget to put an underscore if there is a space in the name, which I forgot to do as seen in image 002.jpg. It should look like "Booty_Shorts, Not Booty Shorts".* You get the point, right? Good.
In the "ITEM NAME" Folder, open the .vaj AND all of the .vap files to make sure the texture .pngs look like image 004.jpg I have posted here and NOT 003.jpg.
Once I see that everything is correct, I then Ctrl A the meta.json and Custom folder, right click-7-Zip-add to archive as seen in image 005.jpg, change compression level to "Fastest", change .zip to .1.var and add a period after the creator name and add underscores where there are spaces as seen in images 006.jpg and 007.jpg. Click OK or Enter.
Test it to see if it works by Ctrl C Ctrl V in your AddonPackages folder.
Everything should now load including presets.
I have been doing this manually with every clothing item that I have converted to var.
I hope this helps someone. I also don't know if this a correct way of doing it, but it works for me.
Also, if there is a faster way to do this, let me know. I have over 2,500 looks/scenes alone that I need to convert from .json to .var.
[EDIT] I forgot to mention a very important step. I added a * before and after what I edited so you know.