Element.Events.extend({
	'wheelup': {
		type: Element.Events.mousewheel.type,
		map: function(event){
			event = new Event(event);
			if (event.wheel >= 0) this.fireEvent('wheelup', event)
		}
	},
 
	'wheeldown': {
		type: Element.Events.mousewheel.type,
		map: function(event){
			event = new Event(event);
			if (event.wheel <= 0) this.fireEvent('wheeldown', event)
		}
	}
});