I changed the diff oil the other day and took a few pics whilst doing so. For grades and quantities see: forum/viewtopic.php?t=9
Pic showing the location of the drain and fill holes (with nuts removed).
You'll need a hex drive or allen key to remove them. The latter doesn't work so well as you need a lot of leverage to undo them.
Replace the drain plug and fill with oil, this is the tricky part. There's not much room around the exhaust pipe to fit a filler bottle. I found a 1l bottle with a pull-up spout that did the job.
It's a tight squeeze when the bottle gets empty:
Replace the fill nut, Torque them both and you are done:
Note: I'm not responsible for anyone causing themselves or their car damage by following the above. It's just how I went about it.