Custom order for next_post_link & previous_post_link?

I’ve got a site that includes a page dedicated to displaying a portfolio of work. As new work is added to the site, I’ll occasionally rearrange the order of how the projects are displayed. I’ve accomplished this by changing a custom field value for each of the posts (projects), and setting them to order by that particular custom field value in ascending order.

<?php query_posts('category_name=Project&meta_key=Lineup&orderby=meta_value&order=ASC'); ?>

That’s all well and good. The problem I’m having is when viewing an individual project. I’d like to have links on this page for the next/previous project for easy navigation. Unfortunately, it appears that using

<?php previous_post_link('%link', '&laquo; Prev', TRUE); ?>

and

<?php next_post_link('%link', 'Next &raquo;', TRUE); ?>

orders the posts by date. I’d like it to stay in line with how the projects are ordered on the main project page and by that same custom field value.

Is this possible? I’m not having any luck figuring it out.
Thanks for any info.

See the site’s project page here.

Regards.
zink