It's not really all that hard, you'll have some screws to remove once from the back side once the air bag is removed from the vehicle.
You can remove those screws and then you have a bunch of plastic tabs (part of the cover) on the sides to lift out at the same time. You'll need to press the back of the unit and the front together in order to pull the tabs outward. Because it is impossible to do this without six hands you can slide small sheets of plastic or something else that won't damage yet will hold the clips open at the same time.
Once you get the air bag removed you'll notice that it is pretty much held together (in other words it won't open up). You have the cover open at this point. On the back side of the crest you'll noticed a flared "dammit" that holds the crest in place. I removed a couple of these before and the quickest way to remove it was to just "DRILL".... I tapped a point and then drilled, take your time, you don't want to slip and go through on the side....
Other than that it's not a big deal....
If you need futher explaination please feel free to ask,
-Eli