Rewrite controller magento

Use the second method but a bit modified. Your XML should look like this:

<admin>
    <routers>
        <adminhtml>
            <args>
                <modules>
                    <Qbikz_ToolTip before="Mage_Adminhtml">Qbikz_ToolTip_Adminhtml</Qbikz_ToolTip>
                </modules>
            </args>
        </adminhtml>
    </routers>
</admin>

Now create the file Qbikz/ToolTip/controllers/Adminhtml/Catalog/Product/AttributeController.php with this content:

<?php 
require_once 'Mage/Adminhtml/controllers/Catalog/Product/AttributeController.php';
class Qbikz_ToolTip_Adminhtml_Catalog_Product_AttributeController extends Mage_Adminhtml_Catalog_Product_AttributeController {
   protected function _initAction(){
       //your magic here
   }
}