That is what you want probably:
Router::connect(
'/:category_alias/:category_name/:id/:whatever',
array('controller' => 'Article', 'action' => 'view'),
array('pass' => array('category_alias','category_name','id','whatever'),
'id' => '[0-9]+')
);
ofc you can delete this validator for id.. or add more validators :)
Then you can use function in ArticleController.php
public function view($category_alias, $category_name, $id, $whatever) {}