I have installed similar noname gimball on my P2. Basically you need 12V, so you can take it from any of 12V rails on the copter. I have taken it from one of the engine connectors, as in here (marked red, sorry I didn't take a picture of already soldered setup).
BTW. anybody else out there who has this kind of setup? How did you calibrate/setup the gimball and it's ranges ? I can operate the motors with the X1 on the default controller, but it seems I cannot go "all the way" down (so that camera would point to the ground) since the cable that connects to the sensor which is under the camera will hit the motor arm.. If I try to rotate and put the sensor to other place, the gimball goes crazy (I suppose it's reading reverse values on some axis). Also the range is way too large to "other direction" (it can turn to film the belly of the copter)..
The Phantom2 software seems to offer much less options in the "gimball" view than the Naza software.. but I read that it's not possible to use the Naza software with P2 ?