[Ozuru]

You can manually set the white balance in Java so there's no reason you can't in C++.

Java code:

CameraServer server = CameraServer.getInstance();
cam = new USBCamera("cam0");
cam.setExposureManual(100); // exposure, 0 to 100
cam.setBrightness(100); // brightness, 0 to 100
cam.setWhiteBalanceManual(10000); // white balance, unsure what max is (10000?)
server.startAutomaticCapture(cam);