Ok here is the 3 step process that is real easy to do. I use a red scuff pad to scuff up the surface and then go over it with a 3000 grit DA sheet. Simple as that. I included a pix of it outside, and you can see it almost matches up to what you might find on a NOS piece, and it's not an overly polished piece.
Thanks very cool. Did you do it freehand or mounted to the car? Those flimsy mouldings look tough to fixture
You should be able to get a red scuff pad at any auto parts store. As for the 3000 grit you will probably have to got a paint, body and equipment store that just deals with body shops or check napa. 3M product. I did this molding off the car but the other 3 I put on the car and used some 3" tape tape to cover up the paint surface. I then screwed it back on and scuffed and then used the 3000 grit and it turned out excellent. Much easier. You will be surprised how easy this truly easy this is. About and hour tops.
You can also use some of this fine wool for a final polish. I've used it with success. They are about $4 a pack at HD or Lowes. http://www.steelwool.biz/