Had some time to ponder your questions, which I wasn't initially understanding. It's been a while since I looked at Antonia's rig. I was assuming the jaw wasn't rigged at all. I'm assuming that the jaw rotation only effects the inner mouth parts (tongue, and lower teeth) and that the other rotations are locked. I'm at work so I can't look right now.

You can add a weight map to those rotations via the joint editor, create new map with that rotation selected in the editor and set it to replace. This will create a map that overwrites the traditional sphere deformer. From there you can paint tweak the rotations. This is how I do it, I rig with traditional spheres and then use the merge to weight maps command (figure menu) which creates maps for all the rotations set as replace. But this is global, you can selectively replace.

As far as the weight map injector goes, nerd has a tutorial for that somewhere on the site. Can't look for it now. Probably he'll respond to your query on the 11 tech forum. If he doesn't I'll track it down when I get home from work and link it here.

This is all off the top of my head, not looking at Poser. If still no response I'll expound further with some images later tonight.