Wiring: Send signal to ps3 gamepad

Hi. I'm trying to give my ps3 controller some extra functions using the ardiuno. Things like disabling a button, adding turbo, combination button presses, ect.

Someone has done something similar and made a short diagram of it. Left Side. I thought it would be wired like the right side where the signal gets picked up first by the arduino and then sends whatever signals back to the gamepad pcb and then down the usb cable to the console. Is either of these schematics correct?

Also I was wondering if I could use one usb(the ps3 gamepad) to power both boards. Something like adding another 5v/Ground wire from pcb usb connection to the arduino. The gamepad draws 3.3v if that matters any.

Thanks for any help.