<?php
$config = array(
    'example-userpass' => array(
        'exampleauth:UserPass',
        'student:studentpass' => array(
            'uid' => array('student'),
            'eduPersonAffiliation' => array('member', 'student'),
        ),
        'employee:employeepass' => array(
            'uid' => array('employee'),
            'eduPersonAffiliation' => array('member', 'employee'),
        ),
    ),
);