I solved my own issue after much research. Here is the snippet code.
<?php
if ($modx->hasPermission('custom_admin_nav_bar'))
{
$user = $modx->getUser('mgr');
$profile = $user->getOne('Profile');
$fname = $profile->get('fullname');
$output = $modx->getChunk('adminBar',array('username' => $fname));
return $output;
}
else {
}
The code basically checks if the user has a permission in their ACL. It then gets the users fullname and sends it to a custom chunk. Basically if a user has access he can see a special admin bar at the top of the screen which welcomes him with his fullname.
Hope this is helpful to someone.