Lightbox2 rel=”” Issues

The way I am creating my gallery is different than what others are doing with plugins (I am using a method by Justin Tadlock), and I am wanting the images to have Lightbox2, but I am not actually coding the anchor or source tags (refer to Justin Tadlocks method) so I cannot add a class or rel tag manually.

Lightbox requires a rel="lightbox", and each image is a bookmark, but I cannot change my rel for these images as the hardcoding in WP keeps me from adding a custom relationship. How can I add a custom rel into the source of wp-admin or possibly change the required rel for Lightbox2?