Get a used wheel without a tire on it. Jack up car and mount wheel and trim ring on car, then run with car in gear. I used some fine sand paper and held it on trim ring while it spun. You can't move your hand back and forth, or you'll get a cross hatch pattern, you have to hold it in place. It may not be perfect, but it will look better than anything after market ring you can buy.
I just did and original polished set I brushed for my AAR and that's exactly how I did it. I used 220 grit paper, anything less just isn't enough.
