Looks like you have to access it through your iPad web browser via an IP address (as long as they are on the same network).
Here's a qoute from 6 Moons:
Scroll halfway down this page to see it: http://www.6moons.com/audioreviews/mcintosh/ms300.html
Here's a qoute from 6 Moons:
Next in line is the choice of IP address so the MS300 can communicate with the rest of the computers in the house. As default IP address, the MS300 uses the generic address 169.254.111.180 with a mask of 255.255.0.0. and uses 169.254.0.1 as its default gateway. We can set it to 10.0.0.22, 255.255.255.0 and 10.0.0.138 respectively for our private network.
We use one of our Macintosh computers to browse the MS300, typing our just configured IP address as the URL into the Opera browser. The MS300 menu pops up within seconds and now displays in full color. From this point forward, the TV screen can be disconnect and the online menu be used instead.
Scroll halfway down this page to see it: http://www.6moons.com/audioreviews/mcintosh/ms300.html