Michael,
Try this:
http://www.caswellplating.com/buffs/bluejob.html
If I remember correctly the rails have a brushed finish that runs around the circumference of the rail! A standard style drill motor would be hard to use because you would have to use it parallel to the rails, and it would be hard to hold. I would suggest that you purchase a 3/8" 90 degree offset drill motor. It would be easier to use. I wouldn't use any compound that would take the brushed effect off the rails as then you would have to refinish all the rails, not just the scratches. Outside of the buff above that I suggested I wouldn't use any buffs bigger than 3 - 4 inches, to hard to control. Try some Simachrome first and see what that does. If that doesn't get it, I would try the white compound.
Let us know how up make out.
John