disconnect the battery, and DOT NOT connect it until you have it all back together (air bag plugged in). Otherwise, your SRS light will come on, and you'll need to get it cleared.
Other than that, it's pretty easy. SOme torx bolts in the back of the wheel (hard to see, they hold on the air bag). The center bolt is 15mm I believe, and you might need a wheel puller to get it off. An impact gun makes the center bolt removal easy.
2007 BMW 328Xi Touring, 6 speed