DX7 throttle set up

Hey all, just picked up a spectrum dx7 - what a unit! - I currently have it set up on a king hauler with an mfc 01. I can't seem to get forward and reverse on the throttle stick, just forward. Obviously the radio is designed for aero use, as planes and helis don't have a use for reverse, just throttle up. Has anyone had success setting the radio up with an mfc 01? There are a bunch of throttle cut and mixing options I've yet to figure out. Any help is appreciated!