Logitech Mouse: how can I use additional buttons?
Thanks to the previous answers, I have successfully used BetterTouchTool to map three different buttons:


Usign "Normal Mice" tab:

Button 3 (Wheel Left)
Button 4 (Wheel right)

Usign "Keyboard" tab:

cmd + D (Back), which I assigned to "Middle click".



Two buttons remain unmappable (Forward and Middle click), but it is better than nothing. Hope that it will fit to your needs.