I edited the 3.7.6 version Windows GLUT source from here:
http://www.xmission.com/~nate/glut.html
The files I edited are in the \lib\glut folder:
- win32_winproc.c
glut_input.c
glutint.h
http://dl.dropbox.com/u/2809326/SpaceNavGLUTChanges.zip
A compiled version of the binaries (Windows 7 VS2010) are here:
http://dl.dropbox.com/u/2809326/glut.zip
I've not tested then rigorously but I've tried them on a couple of our cross platform GLUT apps and it seems to work pretty much the same as the MacOS implementation.
Any feedback welcome (also feel free to post these files somewhere more permanent than dropbox.com).