In Reply to: question about alarm and CD changer on 323i posted by Ming Xu on November 27, 1999 at 21:19:27:
Many people here installed the E46 alarm themselves. Check the FAQ for the procedure. After installation, you need to bring the car to the dealer to activate the alarm.
Simply speaking, CD changer with I-bus is for cars after year 96, which include E46.
The Nakamichi Changer can be installed in the glove box but I don't recommend to buy it for the time being as it is reported to be problematic.
According to what I heard from PacificBMW, the fixed version will come back to market later this year.
Hopes this help.