How can I change the images that are used as backgrounds for the XScreensavers? ie antspotlight and slidescreen both take an image (the same image by default) and that is what the ant walks on or is scrambled.

I have tried all day to find the location of this/these images to change them and I am stumped. The only thing I have seen that might help to configure it is XScreensaver-demo but it is not on my system nor can I find a way to install it.

Thank you for any help you can provide.

OpenSUSE 11.3 using gnome