gistfile1.txt

// appController
public function beforeFilter() {
      /** Auth */
      $this->Auth->unauthorizedRedirect = false;
      $this->Auth->authError = "Sem permissão para acessar.";

      if ($this->_isAdminMode()) {
          $this->layout = 'admin';
          AuthComponent::$sessionKey = 'Auth.Admin';
          $this->Auth->loginAction = array('admin'=>true, 'controller' => 'usuarios', 'action' => 'login');
          $this->Auth->loginRedirect = array('admin'=>true, 'controller' => 'dashboard', 'action' => 'index');
          $this->Auth->logoutRedirect = array('admin'=>true, 'controller' => 'usuarios', 'action' => 'login');
          $this->Auth->authorize = 'Controller';
          $this->Auth->authenticate = array(
              'Form' => array(
                  'userModel' => 'Usuario',
                  'fields' => array('username' => 'email'),
                  'scope' => array('Usuario.nivel_id' => array(1,2) )
              )
          );
          $this->Auth->deny();
          $this->Auth->allow('login');

      } else { // Site
      }
}


//UsuariosController
public function admin_logout() {
    debug( $this->Auth->logout() ); die;
    $this->Session->destroy();
    $this->redirect($this->Auth->logout());
}

//routes.php
Router::connect('/', array('controller' => 'pages', 'action' => 'display', 'index'));
Router::connect('/admin', array( 'admin'=>true, 'controller' => 'dashboard', 'action' => 'index'));
Router::connect('/pages/*', array('controller' => 'pages', 'action' => 'display'));

Router::connect('/:type', array('admin'=>false, 'controller'=>'conteudos'), array('type'=>'conteudos|blog', 'persist' => array('type')));
Router::connect('/:type/:action', array('admin'=>false, 'controller'=>'conteudos'), array('type'=>'conteudos|blog', 'persist' => array('type')));
Router::connect('/:type/:action/*', array('admin'=>false, 'controller'=>'conteudos'), array('type'=>'conteudos|blog', 'persist' => array('type')));
Router::connect('/admin/:type',array('admin'=>true, 'controller'=>'conteudos'), array('type'=>'conteudos|blog', 'persist' => array('type')));
Router::connect('/admin/:type/:action',array('admin'=>true,'controller'=>'conteudos'), array('type'=>'conteudos|blog', 'persist' => array('type')));
Router::connect('/admin/:type/:action/*',array('admin'=>true,'controller'=>'conteudos'), array('type'=>'conteudos|blog', 'persist' => array('type')));
Router::parseExtensions('json');
CakePlugin::routes();

require CAKE . 'Config' . DS . 'routes.php';