That only works if you're (a) wanting to colour an entire bodypart, rather than just a part of it, (b) choosing an area that lines up perfectly with the polygons used to create the mesh (otherwise you end up with a jaggedoutline, as I discussed earlier), or (c) don't need to colour something that covers more than one jointed section.

To take rad's scapula as a for instance... whilst I haven't examined the poser models closely (and have no idea which fiugre rad is using), I would hazard a guess that the polygons in that area do not match exactly to the shape of the shoulder blade. There is no 'shoulder blade' body aprt which can be selected in its entirety, and I wouldn't be surprised to discover that the scapula area is actually spread across two bodyparts - either chest and collar, or possibly collar and shoulder (this is alos quite possibly not the case, but it wouldnt' be a shock if it was). Therefore, simply picking a bodypart and assigning a new material group, or selecting polygons and doing the same, wouldn't work here. We have to resort to control maps and the blender node.

jonthecelt