Why not just run wires through walls?
Presidents of companies want things to be done and work a certain way. It doesn't mean they have to be done exactly the way they think it can be done.
I bet you could find a sleak way to run wires through walls and connect them to a computer.
However, a laptop will only be able to support one additional monitor, unless you find some sort of expander card or something.
What you could do...is have one computer running the 3 plasmas. Then have his laptop use a remote desktop application to control the PC controlling the plasmas wirelessly. And there you go, 3 plasmas controlled by a laptop.
Will the plasmas be all displaying the same thing? If they aren't, things might get complicated.
If they are all showing the same thing, he could simply plug in a cable that is split to all the plasmas, and display things that way.
