The ones for audio CD's will work with data CD's just fine. You can probably buy them at your local software/gamestore or perhaps a Music store.
And as for the direction you are supposed to wipe CD's in... From the inside to the outside in a straight line. Scratches in this direction don't cause too much damage - but I can't remember exactly why. Probably something to do with the amount of data that is lost with a scratch against the track rather than with the track.
