I tested an intuos pen & touch tablet with ubuntu 14.10. But the configuration panel did not show the "Map Buttons..." button.
Thus, I am unable to map them, unless I use xsetwacom. But if I do that, I have both two buttons on the left side respectively from top to bottom button 3 and button 1. When I type in button 2, it lets me configure it but it corresponds to nothing, and I did test many other numbers but I do not find how to configure the two buttons on the right side.
Any help is welcome :·)