ActionScript 3.0 :: Add EventListener To Loaded SWF Instance?

I have a navigation button that loads an external SWF. In this loaded SWF are more buttons (two, to be specific). Right now the goal of these buttons are just to take you to external URLs, but eventually I may want to control the timeline of the loaded SWF with them.

I have successfully loaded the SWF, but I am having trouble getting the buttons in the SWF to work. I have given each button an instance name, but I cannot add an EventListener to either of them. I can add an EventListener to the loaded SWF, but that doesn't really help me.

Here is the code I'm working with:

portfolioNav.pWebNav.addEventListener(MouseEvent.C LICK, pressWebNav);

function pressWebNav(event:MouseEvent):void {
var webStuff:Loader = new Loader();
webStuff.contentLoaderInfo.addEventListener(Event. COMPLETE, finished_loading);

[code]....

As you can see, my button pWebNav loads the SWF called webPortfolio.swf. When the SWF is done loading I am making the content of the SWF a MovieClip instead of a DisplayObject. I remove the EventListener that detects when it's done loading, assign it an x and y possition, and then add it to the stage.My troubles start when I go to add an EventListener to an instance in the loaded SWF. My thinking is because I've cast the SWF as a MovieClip, I can then access the instances within it. Obviously, that's not the case.