I have paid extra for PS "extended" since CS3 but have really never used it's 3D capabilities.  Now that I have CS6, I figure it's time to start getting some bang for the buck.

Very specifically, I want to use PS to help texturing Poser people, V4 and M4, in particular.  I have exported a textured V4 from Poser as an *.obj file and it loads fine into PhotoShop.

What I now want to do, but cannot figure out how to do, is to load a new layer of the skin textures (torso, limbs, face) in order to blend and layer mask areas over the original.  When I duplicate layer from the textures I want to add, they copy over as their UV mapped version, but are not "applied" to V4.  How do I get UV mapped textures on a new layer applied to V4?