How to check if parent variables
You can use your theme's template.php to add a theme_password() wrapper to inject your custom vars:

function MYTHEME_password(&amp;$variables) {
  $node = menu_get_object();
  if(isset($node-&gt;nid) &amp;&amp; $node-&gt;nid == 5) { //Check for display on node/5
    //@TODO: Add $variables altercation
  }
  return theme_password($variables);
}