Yeah.

JCMs lol. Just kidding...

Ask on the 11 technical forum. This is a ghost town for responses. At least there Nerd might decide to answer your query and he's one of a handful of people left, it seems, that can answer such a question.

I've personally never heard of any way of doing such a thing for native Poser WM rigging. Poser WM brush giving you the Blues?