well, I'm not amarcord, but... With the joint editor open, select a body part (in this case, the buttock). IN the joint editor, switch to the bend parameter (using the little drop down box). Make sure that "display deformers" is checked. You should see a red circle and a green circle. Although they ae harder than hell at times to select, select one with your mouse. Your dial area should change to show the dilas for these areas. Using the dials, move the green area around until the look is proper for what you are seeking. Depending on the specific pose, that could require using the rotation or translation dials in single or combinations. It's not the most elegant thing in the world, but it works wonderfully. One of the few things I sorta wish for in P7 is an easier way to deal with those falloff zones -- grabbign one in a multi figure scene is a F***king pita..

thou and I, my friend, can, in the most flunkey world, make, each of us, one non-flunkey, one hero, if we like: that will be two heroes to begin with. (Carlyle)