I'm thinking this out as I type this... You've described (2) possible levels of security.
1. Users
2. Admin
You'll have the following code on that page
<?php require_once( "../WA_SecurityAssist/Helper_PHP.php" );
if (!WA_Auth_RulePasses("Logged in to users")){
WA_Auth_RestrictAccess("login.php");
}
?>
This rule provides access to only USERS. So I would think that you could make a new rule for that page for Admin....
However I don't think that you'll have a lot of success with that as your SecurityAssist doesn't offer a universal login option... or at least I don't think it does.
What I do for that type of activity for my clients is to create a "Admin Backend" web application that lives in a protected directory. In this back end you can create a full new set of tools that would allow you to touch all of your data for all users.
It is really easy to do this if you have DataAssist too.