Hey, maybe I can be of a little help. I just did a head unit install in my '97.
In my car, don't know how it is in the '02, but if you lift up the carpeting on the left side of the trunk, you'll find a control box type thing, where the antenna and other wires are plugged into.
When I ordered the wiring hardness from
Crutchfield, they sent along all new wires for everything I'd need.
Then, you need to route all the new wires from where the control box is (there will be nothing hooked up to it after you're finished) to behind the head unit/wiring harness to plug in not only that but all the controls for the A/C and whatnot.
I guess since you unplug everything from the control box itself you don't need to route them all the way to the front, but all the stock wiring your new wiring plugs into is already in the trunk itself.
Refer to my thread I just made for pictures of the control box and all the wires and plugs that come form the back of the radio.