That kinda depends on how deep the scratch is, and how bad you want it out. The lacquer coat on the wheel is fairly thick, but it is layered. You can't just spray on one really thick coat of lacquer and expect it to stay. I'm not sure how many layers the manufacturer of the LS wheels puts on, but I've heard anywhere from 5 to 15 coats for other companies. And they all vary in how thick those layers are.
If you sand completely through the top layer, you will most likely see a small ring around the spot where you sanded, even after you polish it.