/me slaps forehead.

I remember reading about master/slave configurations when assessing replacement drive options. The new CD-224E *does* work (and works very nicely!), but it needs to be set as master (or slave - I forget which).

In the absence of a drive jumper, this needs to be done by shorting pins 45 and 47 on the powerbook's adapter interface PCB as per these instructions: http://home.comcast.net/~macdan/PB_99_2K_EBM_sled.html

I hope this helps someone else with a similar conundrum! Can mark the CD-Drive as [solved]... now to get the wifi working ...