Yup, I know what you're talking about. I believe the DE litterature made some mention of "tank drive" mode, which is what you want. All it's going to do is have a single "throttle" input, and a steering input, and it will drive the two motors accordingly. Yes, you'll lose the ability to independantly drive each but with that mode in place you really shouldn't need anything more anyways. I plan to accomplish the same thing with a custom V-tail/X-tail mixer in front of the two Viper speed controls I use for my OSCAR.
Kevin McLeod - Oscar II driver