You might want to be more specific as to exactly where it is. I cannot find it in Avsim.New version Fly-By-Wire 2016 01 you can find in avsim.com library.
From Version 2016 Updated:
For one joystick button your can use two commands ( three didn't tested).
- All letters commands are direct to windows (keyboard emulation).
- Added additional four commands Alt and Four commands Ctrl.