Community Auth - Use to selectivly display content on page

Hi all,

thanks for this nice plugin, i had some trouble setting it up but reading helped me big time.

One thing i could not achieve though was content on a page depending on a role.

i tried using 

PHP Code:

<?php
    if( $this->require_role('admin') ) {
        echo '<a href="'.echo base_url(). 'index.php/advertsize/">Anzeigengr&ouml;&szlig;e</a>';
    }
?>

but this leads to the error:

Fatal error: Call to undefined method MY_Loader::require_role() in ...

Which i think is because i am calling this from a .php page and not a Controller.

How would i implement such a thing?

Thanks a lot.
x