function teaser_excerpt() {
	$teaser = get_post_meta(get_the_id(), 'custom_teaser', true);
	thesis_teaser_date();
	echo '				<div class="format_teaser entry-content">' . "\n";
	if ($teaser)
		echo '<p>' . $teaser . '</p>';
	else
		the_excerpt();
	echo '				</div>' . "\n";
	thesis_teaser_link();
}
add_action('thesis_hook_after_teaser_headline','teaser_excerpt',99);

This provides a teaser, with content from a custom feild, or the excerpt if no field exists. Everything except the title and edit link need to be turned off in the options.

Custom Thesis teasers

wordpress

PHP