What do you mean by "work"? I'm convinced that without simulating all the stuff that the brain is connected to, you're going to get nothing except maybe coma or panic, as in "holyshit heart's not beating! lungs aren't breathing! where's the stomach!? where's the liver!?!?" More likely, without that cacophony of signals coming in, the network will just die. So you're going to have to fake that I/O, and make sure the signals respond to brain commands or else panic sets in again.
That may be true if we just remove a human brain and hook it up to computers, but a new brain with no input history would have no reason to expect signals from a heart or lungs, or anything for that matter. As the synthetic brain is stimulated new pathways would form and eventually it would come to predict the signals that it receives. But there is no reason to believe that an unstimulated newly created brain would have any expectations whatsoever.
(Yeah, I'm aware static is background radiation leftover from the bigbang, the above is mostly a joke--mostly.)
Which is why it would be so brilliant to hide their messages in the static. You would have to know what to look for to even know there is a message.
No amount of careful planning will ever replace dumb luck.