How to enable USB android tethering on OS X Mountain Lion without using Easy-Tether (Lite)
I'm guessing this isn't your preference, but the paid version of Easy Tether comes with the appropriate Mac OS X kernel extensions - so you could just pay the one time fee (currently $10) to have this feature programmed by someone who has done the work.

I'm fine with you not selecting this answer, but wanted it here for others that might need a solution that gets around the restrictions in the Lite version of the tethering software.