The stainless can be polished/buffed to restore the original shine. It would be easier off the car so since your painting, they may already be off. Depth of scratches will dictate (he he, he said dictate) the compounds/rouge to start with. If polishing off the car, I would tape small sections of wood inside the trim to strenthen it during the polishing/buffing so the wheel doesn't catch and bend it beyond repair. Of course it could be done by hand a little gentler, but more elbow grease on your part.
Give the laziest man the hardest job and he'll find the easiest way to do it.