first, you need to makea directory inside packages/models to add the model (each model must have it's own directory) in that directory, you either have 1 model, or several with an obj.cfg... assuming it's only a single model, but the model in the directory as tris.obj the skins can be loaded through...

we still don't know all the details... so all I can say

1) make sure your drivers are up to date
2) if you're using an ATI card, turn off catalyst AI, that causes problems with OpenGL