i need to flash my lgu8120 to version 1.01 i have the firmware and flash rw and i have a serial cable to unlock my phone

does anyone know how to add a usb end to the serial cable to make it able to flash my phone i know the cables are only about 15 quid but it is only for two phones so i dont really want to pay out for another cable as i have allready forked out a tenner for this one please please if u have any ideas please help me