I will do my best here:
The first thing you will need is software to track your head, for example, I use FaceTrackNoIR because I want to use my camera.
Second thing you will need in theory is FreeTrack but you won't need it for BF2 (PR) because there's a program made specifically for BF2 and fixed for PR ( link by sirfstar:
https://dl.dropboxusercontent.com/u/997 ... eeLook.exe ).
There is nothing really to set up, first you start as administrator FaceTrackNoIR (or TrackIR software or whatever you will be using, I recommend FaceTrackNoIR), and then you click on Start/Stop in order to start or stop the tracking, then you start BF2Freelook.exe (from the link above which works for PR 1.0+) as an admin too.
And that's it. Now you need to go into a vehicle and turn your head around.
At first it's going to be horribly fast due to the huge sensitivity, but you can tweak under Curves to your liking in FaceTrackNoIR.
Here's my config which has Roll turned off. You can load it by pressing Load profile on FaceTrackNoIR.
http://www.mediafire.com/view/9q8tccgl9 ... efault.ini
Edit: Updated link, turned off roll, and moving on the X and Y axis which seemed to be annoying while flying, now you are only able to pitch, yaw and move on the Z axis (zoom back and forth).
The important thing to keep in mind to avoid problems is to start FaceTrackNoIR and BF2FreeLook before you start PR.
If anyone wants to reword this or add something, feel free.