As previously mentioned, you may array the boards simply by connecting the DO of one board to the DI of the next, as well as the CLK. OE, LE, +5v and GND lines. I simply used trimmed component leads as jumpers.
The biggest factor here is an appropriate power supply. You will not be able to power this via a USB port. A 5-6 volt REGULATED power supply can handle a 6 board array.