How do you reference the main timeline of swf1 from swf2 when swf2 is loaded into swf1?

Question

on this link          http://kb2.adobe.com/community/publishing/918/cpsid_91887.html
I found this script, but I can not use it can anyone help me
// create a variable to reference swf1's main timeline
var swf1Main_mc:MovieClip;  // this assumes that swf1 is a movieclip.
// create your listener to ensure this loaded swf has been added to the display list and can therefore obtain a
// reference to its main timeline (which is always the main timeline of the loading swf).
this.addEventListener(Event.ADDED_TO_STAGE, initF);
function initF(e:Event):void{
    swf1Main_mc = MovieClip(this.root);

Answer 1

You don't make it clear what event finish is for. But let's assume that your MC is being loaded from the clip that you're referring to as root. In the main Document Class of that swf, you'd have
protected var customSwf:CustomSwf;//customSwf is the Class that defines your functionInSwf1protected function someFunction():void {
     var loader:Loader = new loader();
     loader.contentLoaderInfo.addEventListener(Event.COMPLETE onLoaderLoaded);
     //rest of your loader loading code here
protected function onLoaderLoaded(e:Event):void {
      //add to display list (you already know how to do, so I'm not writing the code)
     EventDispatcher(e.target).removeEventListener(Event.Complete, onLoaderLoaded);
     //if you had a legitimate need for path (which you don't) in mcExternal, you'd set it like this:
     this.mcExternal.path = LoaderInfo(e.target).content as MovieClip;
      //this is what you actually need to care about to do this correctly
      customSwf = LoaderInfo(e.target).content as CustomSwf;
Now, the Class that you apply to the library symbol you're using for mcExternal should have code similar to this:
protected function fEvent(e:Event):void {
     dispatchEvent(new Event('giveYourEventADescriptiveNameBasedOnWhatYoureReallyDoingHere', true));
back in your main document Class:
//should probably call from the constructor or somewhere early in the process
protected function init():void {
     //use your real event name--your code isn't expressive enough I could guess a good name
     addEventListener('giveYourEventADescriptiveNameBasedOnWhatYoureReallyDoingHere', onEventHappened);
protected function onEventHappened(e:Event):void {
     customSwf.customFunctioninSwf1();
     customSwf.changeVisualState();//let custom swf change alpha and change the frame #
To the untrained I, this looks like about the same amount of code and slightly more trouble, but changing the design like this will make it much more tolerant of the changes that nearly all clients will want after you've built version 1. mcExternal's code doesn't have to change at all if swf1 changes, and your root Class already knows abotu swf1 anyway, since it's doing the loading, so having it work with it a little more doesn't hurt.
Moving the change of visual state into your custom swf means that changes in that swf won't affect your main document Class, though you will probably have to recompile the main document unless you go to using an Interface (a topic for another day).