Its simple, it does not support more than scrolling left<->right. Press esc or click outside it to exit. Left and right keys work.
<body>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js" type="text/javascript" charset="utf-8"></script>
<script src="lightbox.js" type="text/javascript"></script>
<script type="text/javascript">
$(document).ready(function() {
var lb = new Lightbox({images: [ "predator.jpg", "predator2.jpg"]}); // List the images you wish to display
$("#lb-open").click(function() {lb.open();}); // Setup the div so that cliking it will open our box
});
</script>
<div id="lb-open">Click here to view images</div>
</body>