Found this:
=== Relearning GP Keys ===
All Secondary Keys should be moved away from ignition switch.
Insert Master Key into ignition and start vehicle.
Ready the secondary key in your other hand.
Turn off and remove the Master Key from ignition.
Within 2 seconds, insert the secondary key and turn to Run position.
(do not start car)
when security light turns off (1-2 seconds), turn key to Off for 2
seconds.
Turn key to Run and wait for light to go out again.
This process should be repeated a total of 3 cycles of Run-Off.
Remove secondary key.
To test the key, re-insert and start car.
Light should go out within 1-2 seconds.