According to the diagram you linked to on Bob Robert's site, you would hack a 3 prong AC extension cord and hook the 2 main wires to the 2 terminals marked "AC". The third ground wire connects to the terminal marked "FG".
Bob roberts has a bunch of other stuff connected between the cord and the powersupply (fuse, line filter, on/off switch, dist. block) but this is the down and dirty method if you don't have/aren't using that stuff.
Be aware that the power supply will be "ON" as long as the cord is plugged into the wall. The only way to turn it off is to unplug it or wire in a switch. Bob's diagram was excellent in showing how to wire everything properly. I suggest you study and invite someone over who is more knowledge to help you if you are having trouble understanding it.
Good luck!
One important note: If you are actually using this to power a jamma cabinet and it has the original arcade monitor then I believe you HAVE to use an isolation transformer or you're in for serious trouble. I think the monitor's chassis ends up being "hot" at all times without it... VERY dangerous...