It really works (good enough for me)...
I have added three volumes that are calculated as soft bodies, one for the belly and two for both breasts. The belly and breasts are still animateable to simulate gravity.
The soft body-simulation is not as easy as it can be, you have to play with mass and damping for the goal to get a almost realistic wiggling, when damping is to low the wiggling can get out of bounds for unknown reasons.
Many thanks
Link to model: http://www.mingsing.de/ABTUZIPA/ssbbw.blend