We did a project with CDs at the stamp club I attend, and we stamped directly onto the CD with StazOn ink. We just had to make sure everyone stamped on the correct side of the CD.
I forget which brand of CD we used, but there wasn't much writing from the manufacturer on the actual CD.
I wouldn't suggest trying to glue anything onto a CD. In fact, CD manufacturers, recommend that you DON'T put stickers/labels on them, even the kind that are specifically made for CDs. I've been told that the extra weight can cause the CD to spin improperly and make it unreadable.