There's no wiring involved, and the onboard jumpers allow you some selection in Arduino pins.
Note: To connect a PS/2 keyboard, see http://www.instructables.com/id/Creating-the-PS2-Keyboard-smart-interface-for-micr/
The sample code provided outputs the analog positions of the stick, and the digital positions of the two buttons:
I'd recommend using interrupts for the buttons (pins 2 & 3) so as to not miss button presses, with some debounce code, but that will take some moderate shield modifications. You will probably have to play with your stick adjustments to get zero readings at rest. You can build your own shield, with a female 15p D Sub, and wire it for 2 joystick operation if you want, or stack a second shield. See http://www.built-to-spec.com/blog/2009/09/10/using-a-pc-joystick-with-the-arduino/ for more info. A Y Splitter Cable would allow two joysticks to a single port in this scenario. The joystick Shield above only is wired fore one.