According to my 2001 owners manual, could be different for an 04 :huh:
1. Enter vehicle and close all doors.
2. Fasten seat belt.
3. Place key in ignition.
4. Within 10 seconds cycle key from the OFF position to the ON position FOUR
times ending in the OFF position. (Do not start engine)
5. Within 30 seconds, press the driver's door lock switch in the LOCK position.
6. A single chime will be heard to indicate the feature has been activated.
7. If a chime is not heard, program mode was canceled before the feature could
be enabled. If necessary, repeat.
Like I said, this is the procedure for an 01 so I don't know if it is different for and 04.