Pioneer now has their IR codes for many products on their web site at
[Link: pioneerelectronics.com]I don't see any Cassette Changer nor anything with a CT model number in the devices for which they posted data.
The folders Rob mentioned are here
[Link: hifi-remote.com]I didn't look there for a Pioneer Casette. You could look yourself.
If you find something in either of those places that you think might be your device, you'll probably need some help translating or extracting the advanced codes from it. When you ask for that help, please include the specific URL (page from which the file was downloaded) for the file you want help with.