ActionScript 3.0 :: Loading Buttons In MovieClip As External SWF File

I am working on a website, its a project, I built custom buttons and used there own AS3 to make them play on hover. There is one problem thou, in my main scene or timeline I created this function:

about_but.addEventListener(MouseEvent.CLICK, function(){
var aboutURL:URLRequest = new URLRequest("about.swf");
})
contact_but.addEventListener(MouseEvent.CLICK, function(){
var contactURL:URLRequest = new URLRequest("contact.swf");
})
cat_but.addEventListener(MouseEvent.CLICK, function(){
var galleryURL:URLRequest = new URLRequest("catalogue.swf");
})
port_but.addEventListener(MouseEvent.CLICK, function(){
var portURL:URLRequest = new URLRequest("port.swf");
})

Ok but it had the navigatetoURL function but I took it out. Reason is because I want these buttons to load in a movieclip (mc_loader) as external swf files. I am not sure as is to linking these buttons to the loader movieclip.