Listener.js

// Element Listener Mixin
(function(){

var setup = function(){
	var element = this.toElement(),
		listener = new Events,
		removeEvent = listener.removeEvent;
	listener.removeEvent = function(key, value){
		element.removeEvent(key, value);
		removeEvent.call(this, key, value);
	};
	this.$listener = listener;
};

this.Listener = new Class({

	attach: function(key, value){
		if (!this.$listener) setup.call(this);
		this.$listener.addEvent(key, value);
		this.toElement().addEvent(key, value);
	}.overloadSetter(),

	detach: function(object, value){
		if (!this.$listener) return this;

		if (object == null) this.$listener.removeEvents();
		else if (typeof object != 'string') this.$listener.removeEvents(object);
		else this.$listener.removeEvent(object, value);

		return this;
	},

	toElement: function(){
		return this.element;
	}

});

}).call(this);

// Implementation
var MyClass = new Class({
	
	Implements: [Listener, Class.Binds],
	
	initialize: function(){
		this.element = new Element('div');
		
		this.attach({
			click: this.bound('onClick'),
			'keyup:relay(:input)': this.bound('onKeyUp')
		});
	}
	
});

// Use
var myInstance = new MyClass();
myInstance.detach();