Jenpy,
If the differences in volume and the crease position are not too bad, you certainly could expect improvement in the asymmetries. However, don't put too much faith in the ability of lifting the buttock to affect the appearance of the fold -- it won't move it; it will just adjust the tissue above, hopefully making it look elevated.
Nonetheless, you will have a scar from the buttock lift, but it should be acceptable to you if you are reasonable in your expectations.
One other thought to consider is whether some liposuction just below the fold (at the upper end of the backside of your thigh) would help. It is a tricky area that seems to always want to remain a little irregular after treatment, but it would be worth considering if you have a big asymmetry.
Go see a plastic surgeon with experience in body contouring, and you'll get your best recommendation for how to proceed.
