Want to highlight few options in selected array of checkbox helper

Want to highlight few options in selected array of checkbox helper

1. item a

2. item b

3. item c highlight me

4. item d

5. item e highlight me

6. item g

1-6 are checkbox options
bold options are checked ones(2,3,5,6)
want to highlight 3rd & 5th options

<?php

$pools = array(1=>item a,2=>item b,3=>item c,4=>item d,5=>item e,6=>item g);

$selectedPools = array(2,3,5,6);

echo $this->Form->input('pool', array('multiple'=>'checkbox','label'=>false,'options'=>$pools,'selected'=>$selectedPools ));

?>