Oops, I meant 2 bones = 1 for each breast, not 2 bones per breast. That's be overkill. And yeah, physics hate to loop. We just use a simply dynamic motion within the game engine to control it. The physics is useful for testing deformation within max and getting the skin sorted.
One properly placed joint in each breast is usually enough, unelss you want insane amounts of secondary animation. Then just hand key any motion you want, after completing all primairy motion. Especially for game sequences this hand key process in a ~1 second loop hardly takes any time, and you still retain full control.…