In the sidebar.php of your theme insert the code:
<h5>Other Authors: </h5>
that's how I did it...actually I only present that list on an author page, so the above code is enclosed by an if statement:
<?php if(is_author()) : ?>
<?php endif; ?>
If you need to create links to author pages where the author is listed, you can use the code found here, presuming you are using permalinks. Otherwise, you'd be using ID numbers to create links.
EDIT: apparently, there is a better way... Looking at the list_authors function, I discovered there is a method to create a link that is smart enough to know whether you are on permalinks or not:
$link = '<#a href="' . get_author_link(0, $author->ID, $author->user_nicename) . '" title="' . sprintf(__("Posts by %s"), wp_specialchars($author->display_name)) . '">' . $name . '</#a>';
You must ignore the # symbols in the code because they are needed to prevent the a tags from being interpreted as HTML here.