checkbox Field

 piklist('field', array(
    'type' => 'checkbox',
    'field' => 'checkbox',
    'label' => 'Checkbox',
    'value' => 'third', // set default value
    'choices' => array(
      'first' => 'First Choice',
      ,'second' => 'Second Choice',
      ,'third' => 'Third Choice'
    )
  ));