Controller rewrite

Controller file:

<?php
/**
  * Controllers are not loaded with autoloader,
  * to extend a controller class we need to first call the actual class file
  * ExtendableController is that class fileName!
  */
require_once Mage::getBaseDir('code') . '/core/Mage/ModuleName/controllers/ExtendableController.php';

class Namespace_Module_SomeController extends Mage_ModuleName_ExtendableController
{
/**
 * your controller actions here
 */
}

Config:
see link