Use "Goof Off" to remove the old glue from the rim, you can go to the Zipp website and download their owner's manual where they suggest using that particular latex paint remover (Home Depot). I don't think they are necessarily big fans of the Tufo tape though and I believe in that same owners manual you will read where they comment that people have torn up Zipps when removing the tape.

The Goof off shouldn't harm any part of the carbon fiber but I would try and keep it away from the stickers unless you are removing them.