[Plugin: NextGEN Gallery] slideshow as header background image?

Hello, I just installed the NextGen gallery plugin and am trying to create a rotating header BACKGROUND image using a NextGen slideshow. I have links for my nav bar that need to float on top of the header image. I am using a custom theme based on the WP default. I have tried editing the header.php file as such:

#header { background: <?php
if (function_exists(“nggSlideshowWidget”))
{ nggSlideshowWidget(1,780,200); }
?> repeat-y top; border: none; }

and it doesn’t work, but if i place it in a div tag, it works fine. Is it possible to use this slideshow as a background?