Ok, I finally did my install yesterday afternoon, and it all went pretty well. I found it much easier to remove the stereo a second time, having done some exploratory surgery back in January, and this time I even remembered to reconnect the emergency blinker button. (Thankfully my wife never realized it had stopped working... ) My only suggestion for improvement would be to work on the description of how to connect the circuit to the ribbon cable. I would phrase it in terms of which direction the contacts on the ribbon cable should face WRT the circuit. (e.g. IIRC, when connecting the cable from the CD changer to the board, the contacts should be facing the resistors.)
If you are planning to do this mod and haven't yet removed your stereo you might want to check out my blog entry, where I've posted some tips:
http://www.n8gray.org/blog/2005/10/10#aux-in
The sound is very good! I've only been able to use the headphone out of the iPod so far, but even that sounds quite acceptable. When my belkin kit arrives I'll be using the line out, which should be better. I'll also learn if I have to reopen everything to install a GLI, which will probably be the case...
Thanks again to centerpunch for making this mod possible and jazzymt for making it easy!