Here's the link to my Xdrive DIY that I posted a week or two ago:

http://www.xoutpost.com/bmw-sav-forums/x5-e53-forum/71037-xdrive-transfer-case-fluid-diy.html?highlight=xdrive+diy

You're going to need Xdrive fluid, which I found at ECS Tuning. And yes, the TIS does advise you should reset your adaptation values after changing the fluid. I haven't reset mine yet and I frankly am not terribly worried about it.