I STRONGLY SUGGEST FOR THE PERSON DOING THIS TO HAVE SOME KNOWLEDGE WORKING WITH ELECTRICAL SYSTEMS!
Behind the light switch find which wire WHICH becomes +12V when you turn the headlight switch on, and the just hook up the Ignition wire coming from the ignition switch to that wire. This way whenever the ignition is on so will be the headlights. MAKE SURE YOU PUT AN INLINE FUSE FOR THE WIRE YOU TAKE FROM THE IGNITION!!!