I've used the kit from JCWhitney but it was the same kit I'm sure. A felt pad/mandrel for a power drill and a tub of cerium oxide.
It worked really well on the wife's Camaro windshield but required 45 - 60 min. of polishing to remove the wiper scrapes.
The results were so good I'd do it again - no distortion in the glass either.
Diamondite makes a few kits for scratch removal also.
-John C.