var myRequest:URLRequest = new URLRequest("/someDir/someFile");
var myLoader:Loader = new Loader();
 
myLoader.load(myRequest);
 
myLoader.contentLoaderInfo.addEventListener(Event.OPEN,showPreloader);
myLoader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS,showProgress);
myLoader.contentLoaderInfo.addEventListener(Event.COMPLETE,showContent);
 
var myPreloader:Preloader = new Preloader();
 
function showPreloader(event:Event):void {
	addChild(myPreloader);
	myPreloader.x = stage.stageWidth/2;
	myPreloader.y = stage.stageHeight/2;
}
 
function showProgress(event:ProgressEvent):void {
	var percentLoaded:Number = event.bytesLoaded/event.bytesTotal;
	myPreloader.loading_txt.text = "Loading - " + Math.round(percentLoaded * 100) + "%";
	myPreloader.bar_mc.width = 198 * percentLoaded;
}
 
function showContent(event:Event):void {
	removeChild(myPreloader);
	addChild(myLoader);
}