Pagination with sorting on deep associations

gistfile1.php

$this->paginate = array(
	'limit' => 50,
	'conditions' => $conditions,
	'contain' => array(
		'ExceptionWorkflowLog',
		'Procedure(id,cpt,expected_amount,allowed_total,difference_amount)',
		'Procedure.Claim(id,number)',
		'Procedure.Claim.Group(abbr)'
	)
);
		
$this->set('exceptions', $this->paginate('PaymentException'));

gistfile2.php

<?php echo $paginator->sort('Claim #', 'Claim.number'); ?>