I got wallpapers to work through openx using this method.
First, I created a div below the shell of the contents of my site (using wordpress, the header.php file).
<div id="adbg" style=" margin: 0pt auto; height: 1000px; width: 100%; position: fixed; cursor:pointer; ">
Then I created a div block with a wallpaper image in CSS and added it to OpenX as a TEXT BANNER
<div OnClick="location.href='#';" style="background: url('image.jpg') no-repeat scroll center top #026eb4; height: 100%; width: 100%; margin: 0pt auto; cursor:pointer; "></div>
, openx div ADBG, .
.
, CSS div adbg CSS.