I've been polishing a bunch of stuff lately. I came across a Fordom brand rotary tool which is like a badass Dremel on steroids if you will.
I'm way far away from being an expert on polishing but it aint that hard as I have proven. I have a tendency to screw up most things I touch.
I clean all the crap off the part like roadgrime and paint ect. with brake cleaner or parts washer and then hit it with steel wool to make sure there arent any big nastys that I missed then go with a moderate to fine grit waterproof sandpaper depending on how bad the part looks. Some of my stuff has been buried in someone's back yard for twenty years so I sometimes hit it with a plastic toothed rotary brush to dig out the gouges ect. Once that is done I use a lambswool buffing wheel on the Fordom with white rouge and get after it ! This is the dirty part. lol.
The thing to remember when taking the surface down is that if you put a scratch in it , in order for it to shine real purty like you'll have to buff that scratch out. I'd suggest you experiment on an old cover with different grits and buffers first before doing one you intend to use.
As far as tools all I currently have is the Fordom but am planning to get a bench grinder for the larger parts. I would think that a Dremel would work well for the hard to reach places though and there are a bunch of those.
I hope this helps. Let us know how it works for ya.
Here's some pics of my polishing endeavors.
http://s382.photobucket.com/albums/oo261/nheckler/polishing/