I just got it to work with Joystick Gremlin. It’s a bit complicated, but possible.
What I did limits the virtual throttle to a certain point when not in AB mode. In AB mode, the throttle works normally and if you push it past that point, the afterburner will light. AB mode can be activated by pressing a button and left by pulling the trottle from the AB zone back to the non-AB zone (possible alternatives: pressing the same button again or pressing another button).
After yoiu selected AB mode, you need to move the throttle a bit to actually light the burner, as the virtual throttle will only update when you move the real throttle.