Their instructions refer to Revell's own line of paint, which is not available in the US. If you go to Revell.com, then Revell of Germany you'll see a tab on the left for a paint conversion chart to Testor's Model Master equivilents. (They are intending to offer Tamiya #'s as well in the near future.)
Another source of conversion #'s is www.paint4models.com which is an exhaustive chart with lots of brands, as well as FS numbers, RGB, etc. It used to work online, but for me it doesn't do searches anymore, so I use the download version. It's a valuable resource if you have the time to spend with it.
Another thing you might try is to post the color #'s you're looking for, and maybe myself or other Forum members can give you equivilents from their experience. In a perfect world, Revell would just provide the info right in the instruction sheet!
Mike