I did 400, 1000, 1500, 2000 grit (all wet sanding) and then straight to Maguire's Plastix without the compound in between. I did find an attachment for my drill with just a plain old "sponge type" buffer that I did put the Maguires on so I could get a little more action than just doing it by hand. I got the Maguire's and polishing wheel all at Pep Boys if you have one in your area.
I live in Florida and the sun damage to the lenses was very, very deep. I sanded like crazy at the 400 grit level, then just meticulously at the other levels, then I did the buffer very little in fact, but the buffing with Maguire's at the end is what made them almost crystal clear. My lenses were so sun damaged and Yellow that you couldn't even tell how many headlights were in each unit. Now I did take them off the car to be even more accessible and I wet sanded them in my kitchen sink, the wife really appreciated that part.
My headlights look almost brand new, if I can get mine there I know you can get yours there.