I used the following sandpaper 150, 240, 400, 600, 1000. Unless there are some very deep scrathes in it you can probably skip the 150. Be sure to be VERY thorough with each of the different types of sandpaper, otherwise you will leave scrathes in the surface that can't be polished away at the end. After the sandpaper I used Autosol and finally Slipol(if you know that!?). I haven't done anything to the surface so I'm looking forward to seing how long they stay shiny and mirrorlike.
I did it all by hand so all together I think it took about 10 hours(yeah, I know I don't have a life). I geuss you can do much of the work with some kind of fancy rotating modern machinery. However to get the best finish the final polishing will have to be done by hand.
Good luck ;-)