Vous devrez utiliser le contrôle Flex iFrame. Ce n'est pas une solution 100% flash, et combine un peu d'appels js mais fonctionne parfaitement pour moi.
Vous pouvez saisir le dernier code source de GitHub https://github.com/flex-users/flex-iframe
Voici quelques exemples de code de l'auteur du composant.
<!---
A basic example application showing how to embed a local html page in a Flex application.
@author Alistair Rutherford
-->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
xmlns:flexiframe="http://code.google.com/p/flex-iframe/"
horizontalAlign="center"
verticalAlign="middle"
viewSourceURL="srcview/index.html">
<!-- Example project presentation -->
<mx:ApplicationControlBar dock="true">
<mx:Text selectable="false">
<mx:htmlText><![CDATA[<font color="#000000" size="12"><b>flex-iframe - Simple html example</b><br>This example shows how to embed a simple Html page in a Flex application.</font>]]></mx:htmlText>
</mx:Text>
</mx:ApplicationControlBar>
<!-- HTML content stored in a String -->
<mx:String id="iFrameHTMLContent">
<![CDATA[
<html>
<head>
<title>About</title>
</head>
<body>
<div>About</div>
<p>Simple HTML Test application. This test app loads a page of html locally.</p>
<div>Credits</div>
<p> </p>
<p>IFrame.as is based on the work of</p>
<ul>
<li><a href="http://coenraets.org/" target="_top">Christophe Coenraets</a></li>
<li><a href="http://www.deitte.com/" target="_top">Brian Deitte</a></li>
</ul>
</body>
</html>
]]>
</mx:String>
<!-- Example using the 'source' property -->
<mx:Panel title="A simple Html page embedded with the 'source' property"
width="80%"
height="80%">
<flexiframe:IFrame id="iFrameBySource"
width="100%"
height="100%"
source="about.html"/>
</mx:Panel>
<!-- Example using the 'content' property -->
<mx:Panel title="A simple Html page embedded with the 'content' property"
width="80%"
height="80%">
<flexiframe:IFrame id="iFrameByContent"
width="100%"
height="100%"
content="{iFrameHTMLContent}"/>
</mx:Panel>
</mx:Application>