CakePHP Validate メッセージに変数を入れるとか

var $validate = array(
'password' => array(
'rule1' => array(
'rule' => 'notEmpty',
),
'rule2' => array(
'rule' => array('minLength', '6'),
),
),
'password_confirm' => array(
'rule1' => array(
'rule'=> array('checkCompare'),
),
),
);

function beforeValidate()
{
$this->validate['password']['rule1']['message'] = MESSAGE_1;
$this->validate['password']['rule2']['message'] = MESSAGE_2;
$this->validate['password_confirm']['rule1']['message'] = MESSAGE_3;
}