New posts since last visit

[TurboLaserAWD]

Okay so I used to have this simple code when I had a phpbb board that allowed me to put a number next to the "Posts since last visit" link. It simply showed the numer of posts since the last visit. I really want to get it on my vBulletin board (I have 3.5.1). I've already tried searching many times for something as simple but to no avail. Everything I've tried either didn't work or did more than I wanted it to. I even tried the one by Zachary that looked simple enough and it wouldn't work for me. I use the inactivity/cookie based read marking system.

I know vBulletin uses much more complicated code so my question is this: is there any way to implement the following code that was used on my old board to add a number next to either "New Posts" or in the Navbar at the top right. If so where do I put it and what portions need to be changed to match the vBulletin tables? TIA.

if( $userdata['session_logged_in'] ) 
{ 
 $sql = "SELECT COUNT(post_id) as total 
  FROM " . POSTS_TABLE . " 
  WHERE post_time >= " . $userdata['user_lastvisit'] . " 
  AND poster_id != " . $userdata['user_id']; 
 $result = $db->sql_query($sql); 
 if( $result ) 
 { 
  $row = $db->sql_fetchrow($result); 
  $lang['Search_new'] = $lang['Search_new'] . " (" . $row['total'] . ")"; 
 }
}