I DON"T advise this at all is it VERY tricky to do and VERY hard to get good results...
With that said you have been warned...
With lots of practice and a good steady hand you can smooth out small scratches in the surface of most shinny plastics with a heat gun... As I said it's NOT easy... And the smaller head gun the better, control is everything...
When I worked for Motorola we used to do this to the high gloss phones when they had scratches, but even with tons of (daily) practice it was a 50/50 crap shot at getting it better or making it worse...
LIKE I SAID IT HARD AND SHOULD ONLY BE USED AS A LAST RESORT WHEN YOU CONSIDER THE PIECE A LOSS THAT YOU JUST CAN'T LIVE WITH...