if the 4th gen is laid out the same as the 5th, this is what you do:

1) turn the key to the off position. go to the passenger side footwell. Pull the kickpanel from the center console. If you were sitting in the seat, it'd be the fuzzy panel next to your left knee.

2) under that panel you will see a plastic connector with two sets of wires plugged into it. Remove the set of wires (the one with 2, and the narrower connector), and expose the contacts.

3) bend a paper clip into a U shape and place each end of the U into the 2 contact holes.

4) turn the key to the II position, but you don't need to crank the motor. Watch the check engine light. It will flash a sequence at you. The first set of flashes is the first digit in the code, the second set of flashes of shorter duration is the second digit.There will be a pause between the two "digits" and you can look up the codes.

i'm guessing that 4th and 5th have the same setup so, good luck.