thinkpad X11 wheel emulation for middle button

[Μάνος Πιτσιδιανάκης]

I want to enable wheel emulation for the middle button in my Thinkpad 
(T420s)

dmesg shows:
wsmouse0 at pms0 mux 0
wsmouse1 at pms0 mux 0
pms0: Synaptics touchpad, firmware 7.2


I have already tried:

Section "InputClass"
        Identifier "touchpad catchall"
        Driver "synaptics"
        MatchIsTouchpad "on"
  Option "EmulateWheel" "true"
  Option "EmulateWheelButton" "2"
  Option "Emulate3Buttons" "false"
  Option "XAxisMapping" "6 7"
  Option "YAxisMapping" "4 5"
EndSection

Has anyone configured this successfully?