如何调用自定义模块的admin控制器

如何使用以下代码调用自定义模块的admin控制器。我试着在谷歌上搜索，但无法找到任何

下面是Mynamespace/TypeChanger/Block/Adminhtml/Catalog/Product/Grid.php的代码

   class Mynamespace_TypeChanger_Block_Adminhtml_Catalog_Product_Grid extends Mage_Adminhtml_Block_Catalog_Product_Grid
    {
         protected function _prepareMassaction()
        {
            parent::_prepareMassaction();
            // Append new mass action option
          $this->getMassactionBlock()->addItem(
                    'typechanger',
                    array('label' => $this->__('Change Type'),
                          'url'   => $this->getUrl('abc'),
         //this should be the url where there will be mass operation
                'additional' => array(
                            'visibility' => array(
                                 'name' => 'type',
                                 'type' => 'select',
                                 'class' => 'required-entry',
                                 'label' => Mage::helper('catalog')->__('Type'),
                                 'values' => array('simple' => 'simple','grouped' => 'grouped' , 'configurable' => 'configurable' ,'virtual'=> 'virtual', 'bundle'=> 'bundle', 'downloadable'=>'downloadable')
                             )
                )
               )
                );
        }
    }

 <?xml version="1.0"?>
    <config>
        <modules>
            <Mynamespace_TypeChanger>
                <version>1.0</version>
            </Mynamespace_TypeChanger>
        </modules>
        <admin>
            <routers>
                <typechanger>
                    <use>admin</use>
                    <args>
                        <module>Mynamespace_TypeChanger</module>
                        <frontName>abc</frontName>
                    </args>
                </typechanger>
            </routers>
        </admin>
       <global>
            <blocks>
                <adminhtml>
                    <rewrite>
                        <catalog_product_grid>Mynamespace_TypeChanger_Block_Adminhtml_Catalog_Product_Grid</catalog_product_grid>
                    </rewrite>
                </adminhtml>
            </blocks>
        <helpers>
                <typechanger>
                    <class>Mynamespace_TypeChanger_Helper</class>
                </typechanger>
        </helpers>
        </global>
    </config>