@Fishbot: In the menu, you can set several hotkeys (tracker toggle, view center, reset, axes inhibitor) - You need to enable them first (and set a hotkey).
I have set mine to ctrl+alt+a for view reset, shift+alt+a for tracker toggle.
@Username455: I really only followed the readme:
1) extracted the contents to bin/ of DCS folder
2) fired up FTNOIR, loaded DCS.ini profile from the bin folder
3) confirmed that tracking works, the dropdown menu on the right should read FreeTrack
4) Started DCS -> quick mission
Once the mission had loaded, the head tracker was on and running smoothly. I quit and reloaded the mission, then played through it and landed after success - with no crashes at all.