$ xinput list
⎡ Virtual core pointer                      id=2    [master pointer  (3)]
⎜   ↳ Virtual core XTEST pointer                id=4    [slave  pointer  (2)]
⎜   ↳ Wacom Bamboo 2FG Finger pad               id=11   [slave  pointer  (2)]
⎜   ↳ Wacom Bamboo 2FG Finger touch             id=12   [slave  pointer  (2)]

$ xinput get-button-map "Wacom Bamboo 2FG Finger pad"
1 2 3 4 5 6 7

$ xinput set-button-map "Wacom Bamboo 2FG Finger pad" 3 2 1 4 5 6 7

xinput set-button-map "Wacom Intuos PT S Finger touch" 3 2 1 4 5 6 7
xinput set-button-map "Wacom Intuos PT S Pen stylus" 3 1 2 4 5 6 7

"xsetwacom set "Wacom Intuos PT S Pen stylus" button 1 button 3"