gistfile1.js

// ...
Y.extend(MyPage, Y.Base, {
	
	components : {
		myComponent : {
			requires : ['overlay'],
			initializer : '_initMyComponent'
		}
	},
	
	initializer : function (config) {
		
		this.on('initComponents', function(e){
			if (Y.one('#foo')) {
				e.components.push('myComponent');
				// now if #foo exits, 
				// myComponent will be "eagerly" initialized
			}
		});
		
		Y.one('body').on('click', function(e){
			this.getComponent('myComponent', function(mc){
				// myComponent is for sure initialized.
				mc.show();
			});
		});
	},
	
	_initMyComponent : function () {
		
		// Y.Overlay and all of it's dependencies
		// have been added to the YUI instance at this point.
		return (new Y.Overlay({ render: true }));
	}

});
// ...