Hello Mel,
This scenario relies mostly on 3rd party components not controlled by SAP. As a result, SAP's support is strictly limited to SAP's side of the code which calls external products according to the definition of the GSS-API v2 interface specification (rfc-2743, rfc-2744) with the constraints published as part of SAP's BC-SNC interoperability certification. More details you will be able to find in the SAP note:http://service.sap.com/sap/support/notes/150380 .
And again we strongly recommend for your scenario the solution we offer with SAP Single Sign-On product.
Best regards,
Donka Dimitrova