You should use a good quality floor jack if possible, and use a BMW jack adapter like this one:
http://www.ecstuning.com/ES251251/
Otherwise you'll risk tearing apart the jacking point on the bottom of the car.
Alternatively, you can use the jack that's in the trunk of the X6. It's decent quality and it's sufficient for lifting the car to remove the wheel.
DON'T LEAVE THE CAR ON THE JACK FOR AN EXTENDED PERIOD! Only use it for lifting the car for short periods of time. Use jack stands if you're going to remove the wheel and send it out for repair.
Good luck!