How do you program a 2006 cadillac DTS to a garage door opener?

To program a 2006 Cadillac DTS to a garage door opener, first, ensure the vehicle is in park and switch on the ignition. Press and hold the two outer HomeLink buttons until the indicator light begins to flash, then release. Next, hold the desired HomeLink button and the garage door remote simultaneously until the HomeLink indicator light changes from a slow blink to a rapid blink. Finally, test the programmed button to ensure it operates the garage door.