There used to be a full IDE50 pinout on this thread, but I guess it's gone now. For a non-soldering connection I had used a keyless IDE 40 cable (no bump on the outside and no hole blocked in the end) shoved in one side (bent two pins slightly) and then had a adapter for powering a desktop to notebook IDE adapter (basically a molex with wires going to a connector that goes to a motherboard for switches and HD lights) connected a few pins over. The power connector plugged in 3 or 4 pins from the IDE cable on the bottom row, connecting to +5V and "audio" ground. All grounds are connected together inside the drive anyway, so this worked well.
If you have a multi-meter, you could test the points meddler pictured and the area I pointed out to figure out where to connect power.
meddler: Have considered posting these to Flickr? Would it be OK for me to do so?
mattress: http://www.midwestmac.com/page61.html and scroll down to "CD / DVD Adapter Board - $25.00 - 922-4027
iMac (Slot-load CD/DVD / Summer 2000) "
Also try: http://www.welovemacs.com/9224027.html