I’ve never tried this, so no guarantees, but you should be able to create an iTunes share on your server and just copy your iTunes library to it. When you point the iTunes app to that share it shouldn’t care where it is hosted at as long as it is mounted on the mac with the app. Just copy everything first to test though. You’ll also need to be sure the share is always mounted to. Add it to your login items or use an app like AutoMounter. I like AutoMounter better since it will always remount the share whenever it is available rather than just at login.