Not to push my method, but lookig back it wasn't that hard to do. Your shading zones are not difficult. Try not changing the base model to .obj first - I think you can skip that step. Go straight from the pose, using Convert to Mesh (AssociatedFX) free extension, then bring the new "mesh" into vertex room, then add your new shader zones, then out as OBJ in Carrara - then back and do any other shader adjustments... not too difficult.

Never Give Up!