Hey Olaf,
Download a couple of my hacks and have a quick look at the some of the plugins. You should get the idea pretty quickly on how to do it.
But if you use vBulletin's template hooks, which are in most templates now adays, it would look something like this:
Code:
$template_hook['navbar_search_menu'] .= '<tr><td class="vbmenu_option"><a href="tags.php'.$session['sessionurl_q'].'" rel="nofollow">'.$vbphrase['bookmarksnavlink'].'</a></td></tr>';
If you are finding a location and pasting it exactly then it would be something like this:
Code:
$vbulletin->templatecache['FORUMDISPLAY'] = str_replace($vbulletin->options['sfutbf_ati_text'],$vbulletin->options['sfutbf_ati_text'].fetch_template('UnansweredThreadsByForum'),$vbulletin->templatecache['FORUMDISPLAY']);
Most hacks use either one or the other method for the most part for their hacks, so take a few to pieces and see how they flow. You will soon work out how to do it.
Mosh