firegestures_keypress.js

var event = document.createEvent("KeyEvents");
event.initKeyEvent("keypress",
  	   true,
		   true,
		   null,
		   false,  // holds Ctrl key
		   true,   // holds Alt key
		   false,  // holds Shift key
		   false,  // holds Meta key
		   0,      // presses a special key, @see http://mxr.mozilla.org/mozilla/source/dom/public/idl/events/nsIDOMKeyEvent.idl
		   event.DOM_VK_0  // presses a normal key, e.g. "A".charCodeAt(0),
		   );
document.documentElement.dispatchEvent(event);