NCO 3.0 client connection using gateway - how to configure?

Prepare for a question from a .NET expert but SAP newbie:

We are using NCO 3.0 successfully to connect to both ECC and SAP CRM directly. We have now been asked to connect via a gateway to ECC. We are struggling to configure our destination to do this redirection.

The documentation on connector config seems to be almost non-existent but from what I can see of the NCO classes in Visual Studio and looking at the example config files, defining a gateway with the GWSERV/GWHOST config attributes seems to be associated with creating a server, not creating a client connection to SAP. We are creating a client connection and calling BAPIs to retrieve information - is a gateway valid in this scenario? If so, how do we specify the co-ordinates in our config file?

Any help much appreciated. Thanks in advance,

Richard