Negative.It's a built-in thing to stop people from sharing files across a local network. I hope you noticed that when you turned on sharing in iTunes that it said "For Personal Use Only" meaning just that.
i think you can't since itunes was updated to version 7.
What would you do if you have two kids, both with Ipods, and just a single computer? How would each of them have their own unique library in a single instance of Itunes?