Star Citizen supports the TrackIR protocol, so any method using 3rd party software such as Opentrack or FaceTrackNoIR should work. There are generic instructions on how to set this up.
The game also supports direct headlook but a number of users report problems with this approach - if often conflicts with joystick controls in-game. Should you wish to take the native approach.
- Bind the EDTracker joystick axes to the X and Y view axes in the game. This is done under Options -> Keybinding. Select Joystick/HOTAS and then Advanced Controls Customization at the bottom. Find "Flight - View" and expand it. Then bind the Look Left/Right and Look Up/Down options, and you are done (move your head in the appropriate direction for each one).
- Additionally you can adjust the curves and other options in the Controls Options tab, if you wish.
- To turn off look-ahead mode press AltGr-M in-game.
- To turn off gimbals press LCtrl-G.