Thanks Steve for the replies. I don't know how I missed that device in the builder. I looked several times with different spelling of J.River and media center and didn't find it. But got it first time with your help.
Also, the embedded web page works, but plays the tracks locally on my ipod rather than from the server to my stereo. Is there a way to configure it to play locally with the embedded page while still enabling Gizmo to work remotely?
If not, then I'll go down the other route using the device in the builder. I just like the web control as it gives feedback, shows cover art, etc.