I just did this around two weeks ago. I have a DX, so I didn't have rear speakers, but Honda was nice enough to provide the wiring and cutouts.
I just bought a pair of OEM 6X9s off ebay, which have the right connectors to snap right in to the existing wiring. So your install will be more complicated, although I saw a post around here while I was doing research, and someone provided what the neg/pos wires were on the wiring. Maybe in the "7th generation" stickies or something--it's here somewhere, I know that.
As for getting in there, my first piece of advice would be to pop the plastic fasteners that hold the speaker covers on out from the BOTTOM, i.e., the trunk. I just ripped mine out, and I lost a few connectors. Just use a pair of needle-nose pliers, squeeze, and push up, and the covers come right off. Then you just drop in the speakers from the interior, use the existing screws (or buy some self-tapping screws at the local auto parts place for pennies), and replace the covers (make sure all the plastic fasteners are attached to the cover, line it up, and just pound on the corners with your fist until they're all snapped in.).
