WP-Cumulus is now open source. So instead of going through the documentation below you can download it and have a look inside. See http://wordpress.org/extend/plugins/wp-cumulus/ for more info. You can get the development version which includes the sources from the download page.

To fix an XSS vulnerability, Version 1.23 of the plugin no longer supports calling ‘javascript:’ links from tags. If you need the Flash movie to interface with javascript, I recommend downloading the source files and implementing AS3′s ExternalInterface class to handle communication.