Domino, Apache, and Realms

Gotta a simple question, hopefully with a simple answer.

I want to put an Apache web server and a Domino web server in the same realm, so that when you authenticate to one, you can access the other (or more to the point, so that the other server has some assurance that you are indeed the person it believes you are). [The Apache servers is a reverse proxy server for the Domino server and will reside in a DMZ.]

How do I set up a web realm on the Domino and the Apache side that will include both servers? Is that the only thing I need to do, or does some other blue smoke and magic need to happen on the back end to make this work?

Assumptions:

The user has the same ID on both the Domino and Apache servers.

The user has the same password on both the Domino and Apache servers.

There is no other authentication between the servers – the realm is it.

The only communication between the two servers is via SSL.

Thoughts?