slidepress thickbox background music

hi there,

i’m using thickbox to play pictures aranged by slidepress.
but i cannot figure out how to show the pictures with background music.
i only need one mp3.file playing constantly in a loop.
therefore i have 2 ideas:
– embed audio into the title of thickbox
– embed audio into the wordpress_xml.php from the slidepress plugin.

i tried this code, but it’s not working
<embed autostart="true" height="0" loop="true" src="mp3url" width="0"/>
it’s working fantastic in a page or post but i want it to play whenever thickbox is opening the slidepress gallery in an iframe.
any help is very welcome for this urgent problem
regards