An easy way to do it is to control the exit of air out of the cylinder.
This option is more controllable if you use flow restrictors on the cylinder, to slow the movement of the air. If you don't, the cylinders move so quickly they can be hard to stop at a mid-point. You can keep the system at 60 psi, to give you the force you need - just apply the air more slowly.
Here is a sketch from 2004. You will need to be sure this is still legal with the one solenoid / cylinder rules.
Also look at 3 position cylinders from Bimba. We are using two this year. They are not much more expensive than the same length in a single. They require two solenoids to control them, because there are three ports - one solenoid would control one end and the second would control the extra extension.
NOTE: I assume this set-up is legal with the current rules, because these are effectively 2 cylinders put together, but I am going to ask the Q+A to verify that we can use two solenoids to control this one "combo" cylinder.
http://www.chiefdelphi.com/media/papers/1476