CRM_INTLAY_GET_HEADER_GUID replacement in Web UI

We need to replace the CRM_INTLAY_GET_HEADER_GUID by another

function/method in our CRM 7.0 system. This question was asked here

before and the solution should be to use the function module CRM_ORDERADM_H_READ_OW which can't be the solution because for this you need the Header Guid.

And to get this header Guid we used befor the CRM_INTLAY_GET_HEADER_GUID.

Thanks for any ideas!