Okay.. so you motivated me to searching.. LOL..

IGNITION KEYS
Each ignition key transponder also has a unique ID code that is assigned at the time the key is manufactured. When a key is programmed into the SKREEM/WCM, follow the programming steps outlined in the diagnostic scan tool for "Program Ignition Keys or Key FOB's" under "Miscellaneous Functions" for the "WCM/Wireless Control Module" menu item.
NOTE: A maximum of 8 keys can be learned to each SKREEM. Once a key is learned to a SKREEM, that key has acquired the Secret Key for that SKREEM and cannot be transferred to any other SKREEM or vehicle.
If ignition key programming is unsuccessful, the DRBIII(R) will display one of the following error messages: Programming Not Attempted
The DRBIII(R) attempts to read the programmed key status and there are no keys programmed into SKIM memory.
Programming Key Failed (Possible Used Key From Wrong Vehicle) SKIM is unable to program an ignition key transponder due to one of the following: The ignition key transponder is faulty.
The ignition key transponder is or has already been programmed to another vehicle.
8 Keys Already Learned, Programming Not Done
The SKIM transponder ID memory is full.
Learned Key In Ignition
The ID for the ignition key transponder currently in the ignition lock cylinder is already programmed in SKIM memory.