Hi John,
The simplest way I can think of for this effect would be to do it with a HTML marquee tag and a fixed background-image.
<marquee behavior = alternate direction = up style = "background-image:url(myImg.jpg); background-attachment:fixed; background-repeat:no-repeat; background-position: top left" bgcolor = "yellow">Your text here</marquee>
You can set the marquee direction to 'up', 'down', 'left' or 'right', while you can also specify how many times the text should scroll using the 'loop = n' parameter. There are a few new events with marquee that are scriptable too. Have a look at this link for info:
http://www.javascriptkit.com/javatutors/marquee3.shtml
Hope that helps
Joe
p.s. Remember to specify width for horizontal scrolling, or width and height for vertical scrolling, in px or %.