I have heard tell of these "USB transfer/KVM" cables in the recent past. My guess is that there is client and server software and that it is little more than a network link established between the client and server over the USB. The client/server for the KVM would likely be something like VNC.
I suspect that all you need to care about is the network link of whatever type (Wireless, RJ45, Bluetooth, USB) and effective remote desktop software of your choice (VNC, RDesktop, PC Anywhere).
Whatever solution that might appear, you can bet there will be client side software involved anyway.