The first step that is vital and central in the whole process of how to connect two computers one monitor, is acquiring a switch box that will establish the relevant connection that is needed.
The switch box should have unlimited number of ports where other monitors can be connected to the computer. The more the ports the better chances of having unlimited multi monitor connections.
Adapters have to be there too because this is a multi connection that cannot use one power source.
Without a switch box then establishing a viable connection will not be easy at all. In fact, the main qualification is the switch box. The SVGA cables are pretty important too and it is always advisable to get the cables that are sold with the switch box. It is more convenient and less disappointing because the cables will be a perfect fit.
The thing with this type of computer situation is that the computers cannot both use the computer at the same time. While one is at the null state, the other computer can be easily used. It refutes the need of getting another monitor and yet the one monitor can serve both computers.