inserting sumthin like
code:
$patterns[] = "#\[thread=(.*?)\](.*?)\[/thread\]#si";
$replacements[] = '<a href="http://shoutbox.menthix.net/showthread.php?tid=\1\2" target="_blank">\1</a>';
$patterns[] = "#\[post=(.*?)\]";
$replacements[] = '&pid=\1#\1';
into functions.php should work for like [thread=num][post=num][/thread] returning
http://shoutbox.menthix.net/showthread.php?tid=(n...pid=(num)#pid(num)