Domain Mapping with YOURLS

We are using the Domain Mapping plugin with WP and your YOURLS plugin. We have our admin panel on a different domain than the public blog domain for load balancing purposes. Therefore, we need a way to hook into your core code without editing it directly so that we can add something like the following:

if (function_exists(domain_mapping_siteurl) {
      //the domain mapping plugin is installed
      $post_url = str_replace(get_original_url( 'siteurl'),domain_mapping_siteurl(false), $post_url);
}

To override yourls-link-creator.php line 310
$post_url = get_permalink($postID);