1. Create a custom field for the title with HTML

2. Output custom field on pages you want the HTML
For example, on the single.php page where you would have used
<h1><php the_title(); ?></h1>
Now you use
<?php
$html_title = get_post_meta($post->ID, "HTML_title", true);
if ($html_title) { ?>
<h1><?php echo $html_title; ?></h1>
<?php } else { ?>
<h1><?php the_title(); ?></h1>
<?php } ?>
