How to provide help text for parsers and other plugins?

Is it possible to use hook_help() to provide help text for fetchers, parsers, and processors?

Currently I'm using the following code to provide help text, but the output is a bit ugly- it appears above both panes of the Feeds Importer configuration, and shifts the page down...

/**
 * Implementation of hook_help().
 */
function mailhandler_help($path, $arg) {
  switch ($path) {
    case 'admin/build/feeds/edit/%':
      if ($arg[6] == 'MailhandlerParser') {
        return 'Please see the <a href="http://drupal.org/node/1158574">handbook page on configuring the Mailhandler Parser</a> for additional help.';
      }
      break;
  }
}

What's the best way to accomplish this?