I have a motorola w375 phone and want to charge from a standard usb charger how do I do this

The cable I use is the standard pc to phone type it works on a mac but not on a pc or 12v car to usb plug I have read that u need to use pin x ( the extra pin that does not connect to anything to make it charge ) but WTF my mac usb has only 4 pins not connected to pin X pin 1 and 4 or 1 and 5 phone end have 5v so it must have something to do with the data pins 2 and 3 and without cutting my usb cable in half I dont know if pin x actually has a wire in the cable
I am thinking more on the lines of connecting either +5v or gnd to either pin 2 or 3 to achieve what I want or does the computer use the data lines to tell the phone to charge