Terminal Services and \etc\services port number challenge

We are working with a daemon-like Win2K/XP application that uses
GetServByName() to get the TCP/IP port to listen on. We would like to
get it to work with windows terminal services such that if multiple
terminal sessions are opened, each could have an instance of this
application running (on the same target machine, of course). In order
to make this possible, each instance would have to listen on a
different port.

Now, since there is a single common services file located in
\WINDOWS\system32\drivers\etc, it makes it difficult to have each
instance resolve into different port numbers (the service name is not
configurable).

Is there some way to trick the application to pick up different port
numbers? For example, if it was possible to change the location of
the services file to a unique directory for each terminal services
user, it would solve the problem. Or, if it was somehow possible to
intercept the GetServByName call... You get the idea.

Any thoughts?

--Joe G.