hi, this might help, doesn't look easy though lol. http://www.handa-accessories.com/accord/03-AUDIOATTACH.pdf or this not your year but maybe get an idea. http://www.installdr.com/InstallDocs/Honda/PDF/466005.pdf
Few tips. If you have a hook tool, you will definately need it. And be very careful when pulling out the top piece above the radio (has the hazard switch in it). You can use a thin flat head screwdriver to fit it in between the top part of the radio and that top piece...pry it up a little and then push the piece up with your hands. Its tricky, but easy to damage the piece with the screwdriver if youre not careful. Ive done it alot without any problems....but I work at a Honda dealership.