Create custom page layout in magento

In generally, page template is set under
<reference name="root"> For the set template, mostly using <action method="setTemplate"><template>page/empty.phtml</template></action> and Mark root page block that template is applied <action method="setIsHandle"><applied>1</applied></action> Suppose i am changing template in checkout cart page : <checkout_cart_index translate="label"> <reference name="root"> <action method="setTemplate"><template>page/2columns-left.phtml</template></action> <!-- Mark root page block that template is applied --> <action method="setIsHandle"><applied>1</applied></action> </reference> </checkout_cart_index>
How to apply Custom page layout handles in layout in magento shwoing here..
<custommodule_cms_index> <!-- Custom page layout handles --> <reference name="root"> <action method="setTemplate"><template>page/2columns-left.phtml</template></action> <!-- Mark root page block that template is applied --> <action method="setIsHandle"><applied>1</applied></action> </reference> </custommodule_cms_index>