I've got a simple module that I'd like to release.. but it makes a tiny change in a core file (includes/modules/pages/logoff/header_php.php)

Code:
$_SESSION['popup'] = 1;  //Added to keep popup from going off when you logoff.

// This should be last line of the script:
$zco_notifier->notify('NOTIFY_HEADER_END_LOGOFF');
?>
Now I'm fairly sure I can use that notify thing to launch my one line of code but the instructions listed here:
http://www.zen-cart.com/wiki/index.p..._API_Tutorials

Were a little more complicated then what I'm trying to achieve. Can anyone simplify them? Or perhaps point me at a simple module that uses them?

I looked at my own cart in includes/classes/observers and found the directory empty.. so apparently none of the mods I'm using utilize this feature.

Thank you,
Anthony