i got all my buffing pads for my bench grinder from harbor freight, i got the emory and stainless compounds from Home Depot of all places, Ryobi brand is what they carry here and it works really well, if you can't find any of the compounds locally you can also order them and the buffs from Eastwood. do a google search for stainless polishing and you'll find all the info you can ever use on how to do it.
one word of caution if you are going to use a bench grinder instead of a dedicated buffer motor, the bench grinder runs faster and has less horsepower than a dedicated buffer motor. this can result in a couple problems;
1, since the grinder has less HP sometimes the buff will not be able to keep up enough speed and will stop in the middle of polishing a piece, this won't hurt anything but it can be a pain in the butt having to stop buffing and let the motor build up speed again, only to stop again a little bit later. once you have a little practice under your belt you'll learn how to keep this from happening.
2, since the grinder spins faster than a buffer motor it will have a tendancy to grab your part and chunk it across the garage, this can result in damage to the trim piece, this can happen no matter how much practice you have. if it does happen you'll get a quick lesson in how to repair bent, warped or dented trim.
as far as the bright dipped aluminum pieces go, before you can polich them you first have to remove the anodizing and for that you'll need the coating remover from eastwood to really get it all off. you will hear people saying that oven cleaner wil get it off but it rarely gets it all off, you could also sand the coating off but you could possibly damage the part beyond repair. as far as polishing the parts once the coating is removed it's pretty much the same process as polishing the stainless trim but with a softer buff wheel and a finer polish, usually a white rouge or aluminum specific compound. once you have it polished you'll need to clean it really well to get all buffing residue off and any wax grease so you don't get fisheyes in the clearcoat. once it's all clean you'll want to paint it with a good automotive catalyzed clear paint, Eastwood now has 2-part catalyzed paints in a special spray can that you twist a knob on to release the catalyst into the paint that would work great for this if you don't have a paint gun and air compressor.
compounds
Eastwood Co. - Compound Set Emery - Stainless-Tripoli- Wht Rouge
buffing wheels
Metal Buffing & Finishing: Buffs & Buffing Wheels
buffing videos
Eastwood Co. - The Art of Buffing DVD
spray can catalyzed clear paint
Eastwood Co. - Spray Max 2k High Gloss Clearcoat aerosol