app/code/local/Rom/OgoneFieldLimit/etc/config.xml

gistfile1.txt

    <global>
        <helpers>
            <romogonefieldlimit>
                <class>Rom_Phyderma_Block</class>
            </romogonefieldlimit>
            <ops>
                <rewrite>
                    <payment_request>Rom_OgoneFieldLimit_Helper_Payment_Request</payment_request>
                </rewrite>
            </ops>
        </helpers>
    </global>