Coped from a nice guy.
Once you have the original code (that cant be erased) you may enter up to 3 additional codes of your choice:
Enter the factory set 5-digit keyless entry keypad code.
Within 5 seconds, press the 1/2 button on the keypad to activate the programming mode.
Enter the new personal 5-digit keyless entry keypad code. Each number must be entered within 5 seconds of each other.
After entering the new personal code, press a 6th button to program each new code.
Pressing 1/2 stores the first personal code (if equipped with memory, this code is associated with driver 1 settings).
Pressing 3/4 stores the second personal code (if equipped with memory, this code is associated with driver 2 settings).
Pressing 5/6, 7/8 or 9/0 stores the third personal code, but does not associate the code with a memory setting.
The door locks lock and unlock to confirm the new code is programmed.
This information is also included in your Owner's guide... once you obtain one.