BI4.1 Windows AD SSO DMZ

I wondered if anyone has any information on settings up Windows AD Single Sign on, to work over a DMZ webserver. If I search for BI4 Windows AD SSO DMZ, nothing at all comes back and can't find any definite details on it.

I've configured it inside of a network before now, but never through access from the internet, and a customer has raised the question as to the intricacies of it.

I really just wondered if anyone knew if it was possible, had any white papers etc

Thanks in advance.