Javascript :: Integrate Google Earth Feature Into Flex?

i have successfully integrated Google earth with Flex using ExternalInterface.call("javascriptMethodName") method and writing the javascript stuff in the html file which embeds the swf file. it ran and loaded Google earth successfully.

<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script>
<script src="http://earth-api-samples.googlecode.com/svn/trunk/lib/kmldomwalk.js" type="text/javascript"> </script>

[Code].....

this is a snippet of that html file but when i add something like to the html file:

var directionsService = new google.maps.DirectionsService();