It's FS2Crew.  :P

I'm looking for that addition too on the CS planes, but I can tell you that it takes a SDK to enable the dev from FS2Crew (which is Bryan York) to develop an addon there.
He has to have some dev-like access to the plane's functions and features, so his software can interact with the systems.

I think that there currently is no such SDK for third party devs available for CS planes. I would love to see the 707 with voice command though.  :)
But there is another solution available which I still have to check. Look here.
http://www.captainsim.org/yabb2/YaBB.pl?num=1307639841
http://www.captainsim.org/yabb2/YaBB.pl?num=1307639945