Keyless Entry Programming

I just bought two gmc keyless remotes, does anyone have instructions on how to program them. The dealer wants $30 a piece. Any info. would be great.

Close all the vehicle doors.
Insert the ignition key into the ignition lock cylinder.
Press and hold the door unlock switch.
While holding the door lock switch in the unlock position, cycle the ignition ON, OFF, ON, OFF.
Release the door unlock switch. The doors will lock and unlock to confirm the program mode.
Press and hold the LOCK button and the UNLOCK button simultaneously on one transmitter. After a delay of approximately 15 seconds, the doors will lock and unlock to confirm the programming of that transmitter.
Repeat the previous step to program up to four transmitters.
Turn the ignition switch to the RUN position in order to exit the keyless entry transmitter mode.
Operate the transmitter functions in order to verify correct system operation.

:confused: if i have a 2002 gmc sierra remote can i reprogram it to a 2006 envoy, and if i can will it knock out the other 2 already programed to it?

Anytime you want to "add" a remote to a GM system, you have to program all of the remotes together. Once you enter programming mode, you erase any previous stored remotes and need to program them again.