damn that diagram would scare anyone
I recently installed my Headunit using the instructions from HandA
http://www.handa-accessories.com/accord/accordcd.pdf
Trickiest part is matching the colors of your wiring harness adapter to the wiring harness your aftermarket Headunit came with. Remember to use butt-connectors and get a crimping tool.
You'll be all set and playing tunes in no time!!