Hi, Ronald
Perhaps is too later to offer my solution but if you want, you can test my last implementation for doing what you want.
Excuse me, but my english isn't good and readme file is in spanish.
You can see this thread: http://moodle.org/mod/forum/discuss.php?d=15360#162347, in which is explained my idea, but you must download the file of this post, named "Modif1.5.x.zip"
J. Raúl