function add_to_byline() { ?>
	</p><p class="headline_meta"><?php the_tags('tagged as <span>', ', ', '</span>'); ?></p>
	<p class="headline_meta"><?php echo __('in', 'thesis') . ' <span>' . get_the_category_list(',') . '</span>'; ?>
<?php }
add_action('thesis_hook_byline_item', 'add_to_byline', '99');

This example adds tags and categories to the Thesis byline, each on a new line, and with the needed classes to match the other byline items.

The byline is generated in thesis/lib/functions/content_functions.php (v1.4.2 at the time of writing) look there for code on different byline items.

Custom bylines in Thesis

wordpress

PHP