I guess he means as if painting a sculpture.
Though it would be very useful, I don't think there is anything that does that 
this is what i mean, sry if i didnt explain it very well ^^
like how u can use photoshop with some 3D models... i guess it should be possible if somebody who actually knows about this stuff looked into it, u just need to make photoshop open a brawl model and map the textures like the brawl textures... (sounds easier than what it is i guess...)