you should add an own directive --> there you can listen on('touchstart') for the wanted element (like ion-content or a div).
As parameter you get the touch-event itself --> there you can check the event-properties. there your will find the properties "touches" and "changedTouches". These are arrays with the current touch-objects.. so if you have 2 finger scrolling --> touches.length is 2 and so on.
If the touchstart has more than 2 touches --> make event.preventDefault(); to avoid default behave (like scrolling).