This method doesn't need sandpaper or paint. It genuinely removes the yellowing from the plastic, and is safe for painted on labels and stickers (unless they are paper stickers. I can't vouch for those).
Check the wiki here: http://retr0bright.wikispaces.com/
Again, will post final results once the weather clears up in my area (the method needs UV light and the bulb I bought didn't do a very good job).
Edit: Weather still sucks and looks like it will for a while. Will update as soon as I get some decent sunlight, and then I'll post what I learned.
Before:

After (So far):

Underside of the same part for comparison:

It's finally sunny around here and I've had a chance to do some more restoring. I'll do a write up after a few more sessions, but I want to make sure I have everything down precisely.