R/3 IDoc --> Create a File containing IDoc XML

We need to create a file which contains an IDoc in XML format, from an actual IDoc created in R/3. I have already been able to send the IDoc to XI in XML format. However, I do not know how to use this message being sent to XI to create the file.

In the configuration I tried setting up an Interface Determination which uses the IDoc type as the inbound interface, and has no Interface Mapping. However, when I do this the only End Point type I can choose is IDoc Adapter, but I do not want to convert the IDoc XML back to an actual IDoc again (I want to create a file with the IDoc XML).

Has anyone done this before, or know how to do it?

Thanks,

--Lee