The only real hard part is placing the bones and placing the matSpheres, as Poser's 'load morph target' function is perfectly suited to the mesh blending. I have a feeling that this might be a fairly easy task for someone with some Python skills, which I am not.

The controls needed for the UI would be quite simple, as it should just ask for a source figure, a target figure, and a percentage of target to combine with source. If any JCMs could be converted along the way, that would probably be useful as well.