[FlatheadTed]

On a pre 37 car one cable neg or pos from the 12 volt to the starter terminal on the starter ,Then the other cable from the 12v is touched to start on a head stud or the body of the starter ,On a post 37, One cable to the solenoid on the starter side not the bat side .Then the other wire to earth as on the previous pre 37 .The key needs to be on In both cases the power is kept away from the 6V battery by the starter switch ,This way you are reliying on some charge left in the 6 volt battery to run the coil .you could have a battery charger hooked up to the 6v to boost the 6 volt .