Importing an *.fbx file from Vicon Blade into MotionBuilder

Im trying to import some optical data from Vicon and manipulate the fCurves in the optical filter like you can with *.TRC files, but I can see how this is achieved. Any help or guidence would be great.

Try importing your .fbx file into another 3D app (such as Maya)...you can manipulate the curves from within Maya. Then re-save out your file as an .fbx.