if you mean 3dsmax RTT dialogue it should be possible to define the custom UV channel to any number that is available in your poly at the top of the dialogue.
Didn't know there was a gnomonolgy one, but there is definately the gnomon workshop behind the scenes... http://www.thegnomonworkshop.com/store/product/427/Hard-Surface-Texture-Painting
Collision dummy? On Doom3World they told me you're not supposed to define any collision stuff for your playermodel because it uses some default thing for that...