How to access FlashVars or URL Query String

Question

I am a bit of a rookie with Flash/AS3 and I need help trying to access FlashVars or URL in Object/Embed tags. I've searched in the Internet and the forums but cannot get my head around how to implement this.  Here is my example.
1) ACTION SCRIPT - I have created a simple flash banner with clickable button (sparkle) with a mouse down event.
The action script (AS3) for the button is the following:
sparkle.addEventListener(
    MouseEvent.MOUSE_DOWN,
    function(evt:MouseEvent):void {
        var url:String = "http://www.[site_url].com/as/img.cfm";
      var request:URLRequest = new URLRequest(url);
        var variables:URLVariables = new URLVariables();
        variables.gphc = "382";
        request.data = variables;
        request.method = URLRequestMethod.GET;
      navigateToURL(request);
     *** the core issue to resolve is how to make the line above (variables.gphc = "382";) to be set dynamically.  I would like for the variable to come from the FlashVars or the URL vars
2) OBJECT/EMBED - my object/embed code with include FlashVars and URL Query String
<OBJECT classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,40,0" ID="bannerAD" WIDTH="728"  HEIGHT="90">
     <PARAM NAME="movie" VALUE="http://www.[site_url].com/images/imgs/flash_ad.swf?gphc=382">
    <PARAM NAME="quality" VALUE="high">
    <PARAM NAME="bgcolor" VALUE="#FFFFFF">
    <PARAM NAME="FlashVars" value="gphc=382" />
    <EMBED src="http://www.[site_url].com/images/imgs/flash_ad.swf?gphc=382" quality="high"WIDTH="728" HEIGHT="90" TYPE="application/x-shockwave-flash"  PLUGINSPAGE="http://www.macromedia.com/shockwave/download/index.cgi?P1_Prod_Version=ShockwaveFlash" FlashVars="gphc=382" />
</OBJECT>
Questions that I need answered ... How do we access the FlashVars or the URL Query String?  I have found many references to loaderInfo but no clear way to implement that I'm able to understand. So if the loaderInfo is the key, where do I add in the loaderComplete() function into my action script above in #1?
function loaderComplete(myEvent:Event)
  var flashVars=this.loaderInfo.parameters;
  gphcTextField.text=flashVars.gphc
this.loaderInfo.addEventListener(Event.COMPLETE, loaderComplete);
Any help is much appreciated.

Answer 1

Thank you for your input.  I implemented your sugguestion in the following way without any success.  Notice below in the addEventListner that I have added the snippet of code.  Is this a good place (correct place) to set the local_var?  I did confirm that the FlashVars and URL variables were set.
sparkle.addEventListener(
     MouseEvent.MOUSE_DOWN,
     function(evt:MouseEvent):void {
         var url:String = "http://www.[site_url].com/as/img.cfm";
         var request:URLRequest = new URLRequest(url);
         var variables:URLVariables = new URLVariables();
         var local_gphc:String = LoaderInfo(this.root.loaderInfo).parameters.gphc;
         variables.gphc = local_gphc;
         request.data = variables;
         request.method = URLRequestMethod.GET;
       navigateToURL(request);
Thank you for your help.