I currently work for Terminal 4 at JFK in New York. If you have a B.S. degree and some aviation experience you can work as a ramp controler pretty easily. The training for it doesn't take too long, we're on the 7th fl of the ATC tower here work with many big carriers. Not sure where you are, but I imagine it's not too dissimilar at other airports.Only thing I think you can apply for if you don't have a CTO and are over 31 is a Ramp Tower Controller, as long as you have some aviation experience (ex. pilot).
Here's one of the possible companies that hire for that: