Modifying the album_picturebit template to create a lightbox effect

You could probably use Thickbox highslide for this somewhat easily, you'd just need to tinker with the template code to parse/add in the path variables on the fly. An example of thickbox is here, on a site I threw up for a luthier friend of mine:

http://www.sherman-customs.com/

Same as any other HS and a breeze to set up.