configuring idp to release the "remote_user" as nameid

[David Mansfield]

I have a test IdP and SP both using latest shibboleth and configured 
more or less out of the box.

The IdP sits behind apache with mod_auth_kerb doing http Negotiate 
authentication and passing the REMOTE_USER to the IdP (running in a 
tomcat web container).

This all works just fine, and I get an assertion on my SP (apache with 
AuthType shibboleth) which is valid and allows access to protected 
resources.

However, by default I was getting a transient nameId - some sort of hex  
string, probably a session id or something.

I'd like the users "remote user" as a saml22 persistent nameid, but I 
can't figure out what the correct sourceAttributeId would be (if any).

Any hints?

Thanks,
David