_call.setOperation(_operations[0]);
        _call.setUseSOAPAction(true);
        _call.setSOAPActionURI("process");
        _call.setEncodingStyle(null);
        _call.setProperty(org.apache.axis.client.Call.SEND_TYPE_ATTR, Boolean.FALSE);
        _call.setProperty(org.apache.axis.AxisEngine.PROP_DOMULTIREFS, Boolean.FALSE);
        _call.setSOAPVersion(org.apache.axis.soap.SOAPConstants.SOAP11_CONSTANTS);
        _call.setOperationName(new javax.xml.namespace.QName("", "process"));

//Introducir la cabecera de seguridad
	try{
	        SOAPHeaderElement elSec1 =
	             (SOAPHeaderElement)WSSecurityUtils.createWSSecurityHeader(usuario, password, true);

	        _call.addHeader(elSec1);

	        setRequestHeaders(_call);
	        setAttachments(_call);


donde

  public static SOAPHeaderElement createWSSecurityHeader (String pUsername,
                                                          String pCredential,
			   				  boolean pIsWSPolicyCompliant)
    throws SOAPException
  {

      SOAPHeaderElement elWsSecurity =
        new SOAPHeaderElement(SEC_NAMESPACE_OASIS , SECURITY);
      // ws policy
      elWsSecurity.setMustUnderstand(pIsWSPolicyCompliant);
      elWsSecurity.setPrefix(PREFIX);
      // this is the username token (wsse:UsernameToken)
      SOAPElement seToken = elWsSecurity.addChildElement(USERNAMETOKEN);

      SOAPElement seTokenUser = seToken.addChildElement(USER);
        seTokenUser.addTextNode(pUsername);
      if (pCredential != null) {
        SOAPElement seTokenPassword = seToken.addChildElement(PASSWORD);
          seTokenPassword.addTextNode(pCredential);
      }

     return elWsSecurity;
   }