you can use externalInterface class to expose functions from flex. see code below for flex . The exposed function is accessible from vbscript or javascript in html page.

<mx:Script>
    import flash.external.*;
    public function myExposedFunc():String {
        return "I am accessible from flex";
    }
    public function initApp():void {
        ExternalInterface.addCallback("myFlexFunction",myExposedFunc);
    }
</mx:Script>

I dont know how to write vbscript but flex function can be accessed the same way as we do from javascript . Javascript code is below

<SCRIPT language='JavaScript' charset='utf-8'>
    function callFlexApp() {
        var myText = MyFlexApplication.myFlexFunction();
        alert(myText);
    }
</SCRIPT>

Hey FlexFlash,

To call a vbscript function from flex use this vbscript code in html body tag

<script language="vbscript" type="text/vbscript" >
Function vbFunction()
  MsgBox "function called from flash"
End Function
</script>

Now you can call "vbFunction()" from flex using "ExternalInterface.call("vbFunction");"
below is sample code for flex mxml

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" minWidth="1024" minHeight="768" applicationComplete="callExtFun()">
	<mx:Script>
		<![CDATA[
			
			private function callExtFun():void{
			ExternalInterface.call("vbFunction");
			}
		]]>
	</mx:Script>
</mx:Application>