bootstrap.php

<?php

	// HTTP request
	$request = Request::instance();

	try
	{
		$request->execute();
	}
	/**
	 * HTTP error exception
	 */
	catch (Kohana_HTTP_Exception $e)
	{

		$request->response = $e->getMessage().'[ '.$e->getCode().' ]';
	}

	// HTTP response 
	$response = $request->send_headers()->response;

controller.php

<?php

class Controller_Example extends Controller
{
	public function action_index()
	{
		// Set status to 404 and throw http_exception
		throw new Kohana_HTTP_Exception('This action doesn\'t exist', NULL, 404);
	}
}