It was no big deal at all. It has been about 5 years since I fixed the rattle on one of my 08's. IIRC, I removed 2 screws in the defroster cover and used some felt padding between the cover and the dash---just in a few spots. The padding was the stuff you put on the bottom of a vase or lamp to prevent damage to a wood table top, or on the legs of a chair to protect a wood floor. If you are driving over bumps you can actually reach forward and place your hand on the cover, stopping the rattle or vibration. That will confirm the defroster cover is the problem. Good luck.
Bill