The 2000 Jaguar XK8 doesn't have a built-in garage door opener. The garage door opener functionality needs to be added using a separate aftermarket device, typically a universal garage door opener remote that you'd program to your specific garage door opener. You would then likely mount this remote in your car, perhaps using a sticky mount or a specific mounting bracket.
There's no factory-installed system to program. You'll need to purchase a universal garage door opener remote separately and follow the instructions that come with *that* remote to program it to both your car and your garage door opener.
