At http://www.basta.com/ you'll find a prog, AppToService, which might do the trick. Here's their info:
AppToService is a Windows Unicode console application that lets you run regular applications and servers as Windows services. This allows you to have some of the benefits of a Windows service,
such as the ability to run an application even when no user is
logged on the computer, the ability to run an application under
a specified user account, the ability to allow an application to
survive logoff/logon sequences, hence saving the overhead of
restarting it for each new user, and so on.
For instance, you can run a dialer application as a service to
automatically connect a computer to the Internet following
Stop wishing your application was a service. Make it run like
one with AppToService!