If you can arrange for the receiver to acquire an address from another DHCP server (i.e. DSL router/Linux box), and you can arrange routing from it to the server box, all you should need to do is spoof out the service discovery protocol, to point it at a particular IP address.
See
http://www.mock.com/receiver/server/ for more information.
Getting the routing working might prove problematic. In this case, port-forwarding is your friend.
However, I can't comment on the legality (or lack of) of sharing your music collection in this way.
Roger - not necessarily speaking for empeg