Well, I didn't thought of using ent_mtlset, I thought of loading the fx file into the skin, but it should work with ent_mtlset, too.

Quote:
If I assign a shader to one skin via ent_mtlset, to which skin is entskin1 pointing?


To the skin, which you assigned. The next skin in the entity's skin list will be entSkin2 then, and so on.