It WAS the right guide, but my machine was missing an Airport cable connector, so I had to remove a half-dozen screws and a nut, loosening some black plastic that was screwed under the modem card, allowing access to remove the PCMCIA receptor (tricky getting it unhooked from the card ejector button), then removing the Airport card in order to unplug the cable.

my airport antenna cable has no connector and it doesn't run under the Airport ribbon cable, but instead runs under the PCMCIA card slot to god knows where. urgh, am wondering if I'm following the right guide for my g4, 15: 1.5Ghz Pwrbk.

my g, 15", 1.5Ghz pbk didn't have this cable at all. It's short white kbd cable attached to the trackpad, and it's orange ribbon cable (only) attached to the logic board as in step 12. lucky me.