I've gotten decent results by just flattening the clothing item (scale the z value way down), rotating about the x axis to make it horizontal, drop it to the floor, then apply a few bends, side to sides, rotates on different portions of the clothing, and then apply a wave deformer or two within poser.  This works o.k. some times.

I would like something easier though.  I guess I could have exported the above and tried to create a prop out of it for reuse somehow, but that's not exactly the simplest thing either.