How can I override email template?

In my case, I need to change invitation email template. I'm found set_password_email view in auth_signup module, but I want to keep originaly file. Template is not contain <field name="arch" type="xml"> section:

        <!-- Email template for new users -->
        <record id="set_password_email" model="email.template">
            <field name="name">OpenERP Enterprise Connection</field>
            <field name="model_id" ref="base.model_res_users"/>
            <field name="email_from"><![CDATA[${object.company_id.name} <${object.company_id.email}>]]></field>
            <field name="email_to">${object.email}</field>
            <field name="subject"><![CDATA[${object.company_id.name} invitation to connect on OpenERP]]></field>
            <field name="body_html">
                <![CDATA[
                    <p>
                        ${object.name},
                    </p>
                    <p>
                        You have been invited to connect to "${object.company_id.name}" in order to get access to your documents in OpenERP.
                    </p>
                    <p>
                        To accept the invitation, click on the following link:
                    </p>
                    <ul>
                        <li><a href="${object.signup_url}">Accept invitation to "${object.company_id.name}"</a></li>
                    </ul>
                    <p>
                        Thanks,
                    </p>
                    <pre>
--
${object.company_id.name or ''}
${object.company_id.email or ''}
${object.company_id.phone or ''}
                    </pre>
                ]]>
            </field>
        </record>