mapping keys for wacom intuos3 under blender 2.71

I have an intuos3 and it works under ubuntu 14.04 and blender 2.71xx But at this time I have the default key like the pen, eraser etc.
Now I want to set up the key to do sculpting and retopo but I have a problem identifying the usb wireless mouse at the wacom level.
I can identify my mouse using xinput that provides me with id=8 and usb receiver id=10 But in the wacom setting tablet interface, I cannot find out how to declare the mouse to do zooming in and out using the button 3 and 7?
Can somebody provide some clues as to how to declare a device in that case?