You can get a setup station like the Hudy or the Integy one. You can also measure the distance between the front of the tires to the rear of the tires. This is kind of a tough way to do it but it works if done right. I'd get a setup station. It's much easier and much more accurate.
http://www.speedtechrc.com/store/ebp...nid=384&id=653
This is the one I have and it works just fine. There's really no need to go and spend 5 times as much on the new Hudy one. It's very nice but not really necessary.