it has been a long time since i opened my copy of AM up so can't quite remember but, i would think that that anim is still done with the equivalent of the parameter dials, so morphed if you like, and then just a keyframe anim at the end, same as poser.

It is very easy in poser to simulate this bouncy bouncy boobies, basically when the body goes up the boobs go down, when the body goes down, the boobs go up, when up the boobies will part company, and when down they will be reunited again (trampoline effect)

it only has to be applied in a subtle way to get the effect across! or to affect the dynamics of the cloth,you may use.

i can't see how you can do a 4 min anim with a dance sequence, work on the choreography of that sequence, but then not be prepared to use the body morph dials to "assist"  in the "selling" of the movement, to the viewer, personally i would ONLY use the body morphs to help sell this effect, and not any script that may simulate the effect of gravity on a single body part, as i know i can do it with the dials, but think that there would be a lot of adjusting and readjusting to do with any script, so probally more work than dialling!

i remember an anim that came with poser 5, a really fantastic bit of anim, about a boy at a gym, looking in the mirror at himself, dreaming of having big muscles, can't remeber all of it but basically either he or his reflection starts flexing and growing, posing in front of the mirror, pulling all the bodybuilder poses, and the muscles tightening and bulging (flexing) it was very believable, very smooth, and a slick bit of anim, ...and done using the body morphs!

sorry i don't have a link to wherever that anim is but if you want more info about it, then i will look it up for ya! (name of the anim and or artist)

basically my advise to you would be to take what looks to be the hardest route, and not to look for a simple solution! you'll learn more and get better results.