Instanciar Library em um Helper no Codeigniter

//application/helpers/

function setPagination($total_rows){

$CI =& get_instance();

$CI->load->library('pagination');
$config['base_url'] = _SERVER.'/www/cipadrao/usuario/index/';
$config['first_link'] = 'Primeiro';
$config['last_link'] = 'Último';
$config['next_link'] = 'Próximo';
$config['prev_link'] = 'Anterior';
$config['per_page'] = _PER_PAGE;
$config['num_links'] = _NUM_LINKS;
$config['total_rows'] = $total_rows;

return $CI->pagination->initialize($config);

}