Here's working fiddle: http://jsfiddle.net/4ABMN/4/
I've tested it on Firefox for Android. I followed this guide: http://www.createjs.com/tutorials/Mouse%20Interaction/
Essentially, you need to use framework events instead of straight DOM:
stage.on("stagemousedown", function(evt) {
alert("the canvas was clicked at "+evt.stageX+","+evt.stageY);
})
EDIT:
I forgot to mention, you need to add this line:
createjs.Touch.enable(stage);