When I was playing the second player would mess up from my button pressing. The easiest way to wire the buttons is get a 50pin internal scsi cable and cut one of the headers off.On the 50 pin cable, only 25 are used 1 is a ground there are two rows of 25 top and bottom, both top and bottom wires are connected to the same button so you have actually only 25 pins to be used. Seperate the wires in to pairs of two and connect each pair together to make one so you should have 25 paired wires,but you only need 24 wires so plug the scsi cable onto the encoder. Below the pins are a series of letters.

^abcdefghijklmnopqrstuvwx

The "^" symbol means the first set of wires are groundwires used later on for troubleshooting so tie them aside.Now place each of those remaining 24 twisted pairs into the two european barrier blocks we got, for painless wiring. Now use this simple matix to wire youre buttons. And wire it up!