I am using a TARGET script instead. I get full military power at the A/B detent and then A/B when pushing through the detent. It works perfectly without messing with non-linear in-game curves:
SetCustomCurve(&Throttle, THR_LEFT, LIST(0,0, 72,77, 75,77, 100,100));
SetCustomCurve(&Throttle, THR_RIGHT, LIST(0,0, 69,77, 72,77, 100,100));
You can map a physical axis position with a logical axis position. I have allowed a very small deadzone to ensure there is a small gap between military and A/B. Left & right throttles are different due to the fact they output slightly different values at the same phyiscal throttle position.