I think you don't need to do it because they are powered by USB, but USB hub (if you use) need to be powered.
https://bitcointalksearch.org/topic/m.21486145
It consumes about 5W normally (maybe around 4MH), about 1.5W/MH but it doesn't increase linearly.Please read the thread.
I understand that they can be powered by the hub. What I was curious about is if I could deliver power externally through a bench top power supply. Then I don't have to worry about the hub being able to deliver the required power. So if there are some test points on the board I can deliver power directly to, I would be able to use older hubs I have laying around. In the picture provided we can see that he has soldered power directly to the +5 and ground pins of the usb connector so I can assume that power is being delivered externally. I personally would rather deliver or supplement power somewhere else on the pwa/pcb such as repurposing a test point.