I guess there is no support for Track IR. If you know GRID, you may know that at the beginning there was also no support for track ir headtracking, then with a later patch they added a nice full 6DOF support.
Before that patch, I had used freetrack to use a 2DOF support with the GRID demo.
http://www.youtube.com/watch?v=ZWgCKV41juU
I have not tried shift yet, i'm not at home, but for sure there is the possibility to look up, down, right and left, that is you can use the same configuration showed in the video (above) to have such movement on your headtracker.
Just emulate those controls, and config well the freetrack software, and you will be able to have a good 2DOF tracking in nfs Shift.