depending on how deep the scratches are on it you could use fine sandpaper, like up to 1000 grit then rubbing compound, a coat of wax and it should be pretty glossy. i need to do that to my mirrors.
I'll give that a shot. I just bought a bottle of Meguiar's dual action polisher to take some swirls and scratches out of my paint, if it's safe for plastic I'll bet I could use that. If it won't mar clear coat it shouldn't make the plastic worse.