xinput is a tool used to list any input devices, find out information about those devices and also change settings of any of those devices listed. Questions can cover xinput configuration and use itself and can also discuss input device configuration.
On my Thinkpad I need to execute something like this in the terminal:
xinput set-int-prop "TPPS/2 IBM TrackPoint" "Evdev Middle Button Emulation" 8 1
so that my the 2 buttons on my touchpad emulate ...