Pure AS3 self-preloader

If you mean by "self-preloader" a pure Standalone as3 preloader:

var l:Loader = new Loader();

l.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, loop);

l.contentLoaderInfo.addEventListener(Event.COMPLETE, done);

//this line has to be adapted to the name of your document class

l.load(new URLRequest("main.swf"));

function loop(e:ProgressEvent):void

{

    var kBytesLoaded:int = Math.round(e.bytesLoaded/1024);

    var kBytesTotal:int = Math.round(e.bytesTotal/1024);

    var perc:Number = kBytesLoaded / kBytesTotal;

    trace("PERCENT:"+perc);

}

function done(e:Event):void

{

    //this line for the stuff you might need to visually communicate the loading process and want to remove when loading is done

    removeChildAt(0);

    addChild(l);

}