First you gotta have KotOR Tool its the biggest tool in anyone modding KotOR. Then go under:
BIFs>Items.bif>Auroramodel> Then find the object you want to model.
Also go under BIFs>Items.bif>mdx Then find the same name and extract that one too.
Keep both those files in the same folder then open up MDLops (Download it if you dont got it yet) Then click which game your modding, select your file then click read and write. It will create a new file for you to open in Gmax or 3DSmax. Then there ya go, that should be it i think. Although i skin objects more than model i think i covered it.