There's another thread floating around here about this as well... I don't know about the G37, but the G35 has a separate module found on Canadian vehicles that controls the DRLs. What we don't know is if USDM spec cars came with all of the other wiring harnesses needed to add the DRL module. It would be great for you guys to be able to plug a module and a couple of relays in to the existing harnesses and be good to go.
Maybe Joe at Infiniti of Scottsdale would know based on parts diagrams? He's out today, but will be back tomorrow... 1-888-216-5328
http://www.everythingg35.com
Good luck!
Heath