$builder->add('choice', 'choice', null, array(
    'choices' => array('a' => 'A', 'b' => 'B', 'c' => 'C'),
    'choices_attr' => array(
        'a' => array('disabled' => true, 'data-foo' => 'bar'),
        'c' => array('disabled' => true, 'data-foo' => 'bar'),
    ),
));

$builder->add('choice', 'choice', null, array(
    'choices' => array('a' => 'A', 'b' => 'B', 'c' => 'C'),
    'choices_attr' => function ($choice) {
        $attributes = array();

        if ('A' === $choice || 'C' === $choice) {
            $attributes['disabled'] = true;
            $attributes['data-foo'] = 'bar';
        }

        return $attributes;    
    }
));

$builder->add('choice', 'choice', null, array(
    'choice_list' => new SimpleChoiceList(
        array('a' => 'A', 'b' => 'B', 'c' => 'C'), array(), array(
            'a' => array('disabled' => true, 'data-foo' => 'bar'),
            'c' => array('disabled' => true, 'data-bar' => 'baz'),
        )
    )
);