title: How do i override the "addAction()" funciton under app\code\core\Mage\Checkout\controllers
body: <p>I am trying to add some data to a session variable when a product is added to the shopping cart...</p>
  
  <p>I tried copying the "CartController.php" under "app\code\core\Mage\Checkout\controllers" to 
  "local\Mage\Checkout\controllers" but its not actually overriding the controller..</p>
  
  <p>Could anyone give me some hint on this..?</p>
  
  <p>Thanks a lot.</p>