Codorna, imagino que você já tenha conseguido resolver, né? Nós integramos com Salvador e no final, o "envelope" é algo assim:
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns="http://tempuri.org/">
<SOAP-ENV:Body>
<EnviarLoteRPS xmlns="http://tempuri.org/">
<loteXML>
<?xml version="1.0" encoding="UTF-8"?><EnviarLoteRpsEnvio xmlns="http://www.abrasf.org.br/ABRASF/arquivos/nfse.xsd"><LoteRps id="001"><NumeroLote>1</NumeroLote><Cnpj>.......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</X509Certificate></X509Data></KeyInfo></Signature></EnviarLoteRpsEnvio>
<loteXML/>
</EnviarLoteRPS>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>