As I see no documentation or place to "get the code" from the page you mentioned, and it doesn’t even work intuitively on the demo(the bottom row previes get cut off by the ads so you can’t even see the "caption" that should show up…) I’d suggest qTip, a jQuery plug-in
Here is the site for it, http://craigsworks.com/projects/qtip/
Here is how to easily use it as an image [url]preview http://craigsworks.com/projects/qtip/de … ent/images[/url]
Here is how to position it, http://craigsworks.com/projects/qtip/features/#position
Looks quite easy to use.