When trying to bind keys using InfiniBar-2.0 I was able to bind keys to the primary left and right mouse buttons (buttons 1 & 2), to the mouse wheel (button 3) but it did not register the two buttons on the side of the mouse (buttons 4 & 5) for some reason. I use a pretty standard 5 button, optical Logitech. I don't have the exact model since I'm not in front of my gaming rig. I was wondering if anyone else ran into a similar problem, and what they might have done about it.
Not a fix as far as your addon is concerned but you could install the UberOptions mouse package over your existing Logitech drivers. UberOptions usually allows you remap all the buttons on your mouse to other key presses etc (I use it so I can remap the stance danceing on my warrior to the middle multicroll direction wheel thing).