What I used in my 2003 Accord EX is the SNHOND3 adapter from Soundgate. You might find the following web site useful:

http://www.distantcreations.com/accordipod/images.html

While this site talks about connecting an iPod in a 2004 EX, I took the exact same steps to connect a Creative Labs Zen MP3 player. Many people that have used the SNHOND3 talk about a problem with hiss which is why the ground loop isolator is used.