Here’s the dx-button mapping section of my key file, for NXT+SEM, if anyone wants it as a starting point.
https://pastebin.com/QxksiHKP
Quick guide to how I laid out SEM and the base buttons…
F1-3 => autopilot switches, for convenience
A1-A2 => autopilot paddle switch, and ap-disconnect switch
SW1 => uhf/vhf comms (ptt) also cursor-zero, for convenience
SW1- shifted => dogfight/mrm/cancel
SW2 => speedbrakes in/out, toggle
SW2-shifted => gear up/down, hook toggle
Red button => emergency jettison (shifted => eject)
B1-3 => convenience buttons for left/right trim
M1-4 => countermeasure program selector
C1 => visor toggle (shifted => nvg toggle)