$form->add(
	'Multiple Checkboxes',
	'multicheck',
	FORM_INPUT_TYPE_CHECKBOX,
	false);
$form->setValueType(FORM_VALUE_TYPE_ARRAY);

$form->addValue(
	1, 'First');
$form->addValue(
	2, 'Second');
$form->addValue(
	3, 'Third');
$form->addValue(
	4, 'Forth');

// and once form has been submitted you can check by
$checkedvalues = $form->get('multicheck');

// var_dump($checkedvalues); should give you an array of the checked items