There are 3 excellent ways of setting up your split elevator without buying a new transmiter. Both JR and Futaba make a product for plugging up to 4 servos on one channel. JRs' is called the Matchbox. I don't know the name of the Futaba product. JRs' sells for around $70.00 each or 115 per pair. Both will let you reverse one or more servos from the matching unit. Both will let you PRECISELY match the center and end point positions of the servo. A very desirable condition. Both are small and light.

If you are using Hitec digital servos, you can purchase one of Hitecs' digital servo programmers and set both servos to the condition you wish them to be. You can also match the servo speed, center, and end points for perfect control harmony.

Those suggesting using a "Y" harness with a reversing function are setting you up for a lot of problems. It's also very old school thinking. Some of them are changes of control position as the reversing switch gets warmer. Inaccurate servo adjustment through the reversing pot, poor servo centering, and differences in servo speeds. All cause problems. Using the newer products using current technology will save you a lot of time and grief. It may cost you a little, but it may also save you more than you want to lose.