Coolsculpting is a fantastic procedure and works very well on the buttock area. It takes a total of two hours to treat the buttocks - one hour for each side. It especially works well if the buttock area is sagging when combined with Thermage. An in office consultation is the only way to determine if you are a candidate for Coolsculpting.
Like others have said, Coolsculpting can be used in the buttock area if there is pinchable fat. I have performed this procedure many times on the area under the butt called the banana rolls, and we have seen great results. Right now there is no applicator designed to treat the buttock itself. Best of luck.