The Fac rims can be "eye catching" and look great on these cars and the first "work over" of the rims is the most time consuming and successive polishings are easier. If you are changing out tires, do this process between tire changes and with valve stem removed. I WOULD NEVER ATTEMPT DOING ANY POLISHING WITH THE CAR JACKED UP AND WHEEL SPINNING (as a lathe). Good way to end up with a broken wrist by catching the "slot " holes in the rims themselves, or the valve stem with the towel or polishing ball.)
My process is as follows; Remove the wheels from the car, remove the center cap (careful with the screws, they like to seize and break off) and clean with a good de-greaser like Simple Green. If the rim has bad "curb rash" and/or gouges on the face of the rims, then you may want to consider replacing the rim as any material that is missing, can't be replaced, just "worked down" (or the worst rim becomes your spare). I'd be very careful with any sandpaper as the aluminum is soft. For raised 'burrs" from curbs, I use a flat metal working file and gently remove the high spots, trying to make sure I don't do more damage in the area. The "concentric rings" on the outer rim, referred to earlier are very tough to "save", but can be replaced on a metal lathe if your so inclined, mine just are polished out and I've never had points deducted.
Now you're ready to polish. I've had very good results with using the Red Foam Ball (with stem that can be mounted in a handheld drill) from Mothers and the Mothers polish. Place the rim on a flat surface and be liberal with the polish. Follow the instructions concerning keeping the Ball damp. The foam will start to disintegrate after some use and I've used several balls sometimes for a set of 5 rims (spare). And I find the balls disintegrate between uses no matter how much I clean them. I do cleanup the rim with Dawn dish soap to remove any remaining polish and its base. If I have the "good" tires mounted, I'll tape the area next to the rim the best I can, as splattered polish can leave "grease shadow" that is more work to remove, but eventually blends in. I have treated the rims (when dry, in the sun hopefully) to a transparent finish such as Shark Hide (sp?) and find it helped substantially prevented re-tarnishing. tTe "Slots" in the rim (5) are rough cast and not machined. I've polished those areas but never get a reflective finish like I do on the outers. The hand held drill/ foam ball is the way to go - let the drill do the work. Takes about an hour for each rim. Good Luck. Big Al