I don't have a direct answer for you, but may have a useful alternative.
I have worked with many computers of various flavors and long ago gave up the idea of switches for the various displays and keyboards and whatnot. Just too much of a pain. Instead I use exported displays (X windows for unix/linux, RDP for Windows). That way I can sit at exactly one monitor and see any or all of the machines with one keyboard and pointer. To avoid confusion I tend to put each machine on a different desktop, but that's just my preference. Using exactly one set of HID's makes the "feel" of each computer the same. An added advantage is that it is possible to cut-and-paste between computers, something I use more than I expected to.