Add an observer: Magento extension etc/config.xml example (extensibility alpha-1)

config.xml

<config>
    <global>
        <events>
            <customer_delete_commit_after>
                <observers>
                    <customer_deleted_event>
                        <class>Mage_Customer_Model_Customer_Webhook_Observer</class>
                        <method>dispatchCustomerDeletedEvent</method>
                    </customer_deleted_event>
                </observers>
            </customer_delete_commit_after>
        <events>
    </global>
</config>