An A500/A2000 Kickstart rom will work fine in the CDTV. The "extra code" is stored on 2 other smaller ROMs at locations U34 and U35. A regular Kickstart switcher will work but you have to upgrade the CDTV ROMs to at least version 2.3 for the CD-Rom drive to work with 2.04+
Hope that helps. I can help some on this as I have the upgraded ROM's and a self-made Kickstart switcher in mine.
CDTV ROM Information-Jeff
