Is there any way to add custom skins in MCA?

I am a skin creator, and I'd love to be able to see some of the skins I've made in my Minecraft comes Alive village. Is there any way that I could do that? I have tried going into the files by changing the mod's file from .jar to .zip, unzipping the mod, and then adding in the skins myself. I then re-zip and convert back to .jar but the game always crashes.

No, don't change the file extension! Windows warns you about the file corrupting, and that is what you are facing. Open it with WinRAR, then go find the skins folder, then you can find the skin you would like. After you find it, just replace it with the new skin. I'm not quite sure about the "converted" type of png file because there will show up two but I'm sure you can figure it out!