[Exim] Conversion questions to v4

I ran the conversion script to make my exim v3 configuration compatable
with Exim v4. I know there is to be some editing, but I think there is
some kind of bug somewhere in the script because I saw a few lines in
the new file that looked like:

relay_to_

Now that could be just me but it sure looks like a piece of a broken
configuration statment.

Anyway, after reading through that file and the sample exim.conf file
provided in the source tarball I have many things almost ready. However,
there is still one thing I have not been able to determine yet. Because
of restrictions placed on me by my ISP I have to route all my mail to a
single server. They want it to be their server, but that is not going to
happen in this existance while their mail server is NT. So I have my own
server on the net that uses port 4000 (to bypass their port 25 blocking)
as well as port 25, and then my server that sends/recieves on port 4000
only. I can not see from the converted file how you would set something
like that up in Exim 4.

Any help is greatly appreciated!!

-- Dan