The buttons are indeed mapped backwards because I think backwards. When I think of turning the volume down, I think of turning a knob in a counter-clockwise direction, and vice versa.

But you're right, the syntax listed in that thread is indeed broken. It was a cut and paste error. The lines in question should have read:

AD520A.L=b

AD520B.L=a

B is the code for knob uh... left I think, and A is the code for.. the other one.