For what it's worth you don't need the Logitech Control Center installed but some features won't work (eg. scrolling with the thumb scroll wheel, "search" button). I personally have had issues with the software - at least it's no longer an APE application (but now it's an InputManager)
That said, as said by Dave Cheney the place to get Expose and Dashboard to work with buttons is in the Expose & Spaces Preference Pane.
The mount button numbers correspond as such (without the Control Center installed):
Mouse Button 5: The "forward" button
Mouse Button 4: The "back" button
Mouse Button 9: Rotate all the way forward on the thumb scroll wheel.
Mouse Button 11: Rotate all the way back on the thumb scroll wheel.
Mouse Button 13: Clicking the thumb scroll wheel
I suspect that with the Control Center installed left and right on the main scroll wheel and the "search" button will actually be recognized.
That said the Logitech Control Center settings are saved in