Just lowered mine. The front and read lowering is done the same as you would lower the front on a C5.
Same 10mm nut. When you jack up one side you can make the lowering very easy by using a jack stand or another jack to hold the car off the ground then take another jack, put a small block of wood on it, then jack the black fiberglass leaf spring close to where the lowering bolt is just enough to take the tension off the lowering adjuster. By doing it this way (and squirting a little wd-40 on the threads of the nut) I was able to hand turn the bolt.
You should pick up about 1" or a bit more and your car will look sweet.
Oh, and turn the bolt counterclockwise as if to loosen a nut!!
Bob