Do a search on youtube for fitting a motocross tyre, have a good look and give it ago it really isnt that bad if your in a clean warm area, take your time and lube well
This guy is a good one to watch
http://www.youtube.com/watch?v=qw0B2gIwbBg
Although he does make it look remarkablly easy, its more about technique than beating the crap out of it