Yeah dont worry, its simple, you just have to do the same to the other key within 15 seconds or so... Hmm looking at the link its somewhat right i think, but take a look at this one instead:
http://www.xoutpost.com/articles/x5/...ob-bmw-x5.html
Try the turning it to position 1 5 times then doing it
I think thats what i had to do with mine