$user = ORM::factory('user');
$user->username = 'philisgay';
$user->password = 'password';
$user->passwords2 = 'passwordasdfadsf';

try
{
    $user->save();
}
catch(ORM_Validation_Exception $e)
{
    // Passwords don't match hence we are here
    echo Debug::vars($e->errors('models');
}