To enable multitouch, i.e. 2-finger scrolling you have to install gpointing-device-settings which is a gui tool for setting pointing devices. Currently it can configure mouse type device (mouse, trackpoint etc.) and touchpads. For mouse you can configure middle button emulation, wheel emulation and scrolling. It can enable and disable touchpad, or scrolling on it as well as additional parameters like palm detection, locked drags, tapping and scrolling. It is a successor of gsynaptics. Once installed it should appear in the mintmenu as Pointing devices under Preferences.
sudo apt-get install gpointing-device-settings