Yeah, any channel that will center the servo is fine. The problem with using the throttle channel is that you really don't have a 'zero-ing' point on the stick. The others will go to center, and as long as you center or zero the trims, you are all set. The Spektrum, for instance, has an LCD display that shows the trim position, which makes it real easy to both zero the stick and the trim. I'm sure others have that feature, but I am not familiar with them.

There is another gadget that I bought a while back which uses a gizmo that behaves like an RX but is actually a USB device which allows you to control the servo on a PC via the installed software. TXServo is the device and here is the link:

http://www.txservo.com/

This may be more than an average RC'er would use, but I find mine pretty helpful in setting up servos and doing such things as setting up the throttle, and other controls. And, it fully exercises the servos.

CGr
CGr