Another way of starting out with it (and what I did), was to work out the speeds required for each level of the test, then programme it into a treadmill. It was great for getting you used to running at different levels of speed over the nine or so minutes you will be doing the test. Obviously it doesnt practise the turning, but I can't say I had any real trouble with this - all though we did do it a few times at school in football training sessions, so I guess I have some experience of doing it.
Then get out there and practise the real thing!
I used this treadmill technique, and to counter the decelerate, turn, accelerate bit, I started the test at 2kmph faster than the real thing, so basically you had to score two levels higher than in real life. This may help too