Howdy, congleal...
I added 'bgsound' => array('class' => 1, 'id' => 1), to play a sound on mouse over at one point. Worked fine... annoying as hell. I'm not sure I needed to have 'class' and 'id', though.
All $_CONF['admin_html'] does is tell GL what tags to not strip out. You have to know what code you're going to use then add the tag (or tags) to that section so it won't get stripped out... then add the javascript or whatever your going to use where it needs to go.
Hth