That's exactly what I do to!!😛
I think the CD insleeves are about 12mm x 12mm, although I can't remember if that's exact!!
Layout in either Freehand, Illustrator or Photoshop......
I made my own CD templates by measuring a CD's diameter, the the subsequent hole in the middle and the actual playable area and layed it out in Illustrator, always came out ok for me!!
I've got a really great material for sticking onto CD's, it's like sticky back plastic, but you can print photo quality images onto it, and then it sticks onto the CD, careful use of a scapel and you have a top quality finish.....