Each retexture for the models has its own similar file structure. There are technically 2 ways to do it. The first is adding and removing files yourself under the (Yiffalicious_10_64bit/custom skins) and then adding your .zip retexture. The second way is to use the YiffaliciousSkinManager V2.03+ by jei3 and using that system. (its basically the same thing but allows to you drag and drop skins.)
You can also get the base files from the Yiffalicious website to start your retexturing journey.
If needed there is a great collection of other retextures by
qoofi a page back from here that you can use to see how each mod is structured per model. You can also check mine too if needed from my Mega linked below. You can also download the skin manager on my mega too if you cant find the original from jei3
Special things to note that I noticed while doing my own retextures.
• You can change the eye color of some of the models and some don't change well. Example is Bunny has a blue hue that I still can figure out how to change.
• Every model mirrors one side except for Khana where her arms are separate.
•You can hit F5 in game to reset the textures to change them in real time to test.
• You
cannot add bump maps or specular maps, only base textures. The models, such as the dragon, have a bump map on them that you cannot turn off.
• A few characters are also able to have a fur setting in the options you can turn on. These take info from the texture map and superimpose it onto the fur. I would recommend testing the limits before going in full force on it.
• Probably goes without saying since you can import models but you cannot edit the models geo at all or re-UVmap them.