Exim4? Smtp through a smarthost

[Jacob S <stormspotter@6Texans.net>]

Hello list,

I have Postfix setup as a smarthost and working great. But now I need to
setup another smtp daemon to use the smarthost. I need to be able to
specify a non-standard port to talk to the smarthost on and the username
and password. 

It looks like this should be possible with exim4 and maybe nullmailer as
well, but I can not find both requirements in their docs or with my
google searches. I am open to solutions using exim4, nullmailer,
postfix, smail or almost anything available via apt-get in Sarge.

Can anyone point me to their favorite tutorial, or provide an excerpt
from their config file that does the non-standard port, username and
password to relay through a smarthost?

TIA,
Jacob