It might be do-able, might. In '04 they changed the wiring from 'World Plugs' to 'Phase II', you would have to buy two adapters one for body side and one for the radio side (Metra has them). Then you have to spice the 36 wires together to bridge the two (plus 4 if you have the sub). With an '02 you should have World Plugs, Nav radios are all phase II's.
Aftermarket is an option now, as they make adapters for the steering wheel controls.
Word of caution on the JY or fleabay buy, usually the CD unit is broken if the shipping bracket is removed and its turned upside down. The only thing holding the CD trays is a very small spring and a small post. The trays will fall off jamming it up good. I added Audiophile 6CD (fleabay $50) to a basic Radio in my '04, after i got it in the mail well packaged, i had to send it out to be fixed (Another $80). So far after a year all is well.
hopefully this helps