This is possible, but it means editing some code to do it. To create the area in a format that Google maps can use you need to use a service like this one:
http://www.doogal.co.uk/polylines.php
Copy the text from the code tab and then search in /js/maplistfront.js for the following:
//Default map view
var mapTypeIdToUse;
and then paste this in directly before. Then add these two lines after:
polyline = new google.maps.Polygon({path:path, strokeColor: “#FF0000″, strokeOpacity: 1.0, strokeWeight: 2});
polyline.setMap(self.map);