[Zope] how to override SERVER_URL?

[Roman Milner]

I need to override SERVER_URL so I can trick Zope in to giving me the
correct base href. I can't figure out how.  I tried exporting it as an
environment variable, and putting it in the http headers - but neither
worked.  Can anyone help? I'm runnig ZServer without apache.

FWIW, the reason I need to do this is I'm trying to write a simple
load balancing proxy server with failover support that works at the
http level and not at the tcp level for use with ZEO. The problem is
the base href returned to the client points to the actual zope server,
not the proxy server.

Thanks,
^Roman