The light is permanently live and the earth is switched by the GEM, the interior light does come on when you unlock though for a pre determined time, so clearly it has an earth output you may be able to use to trip the relay and of course the lights will only stay on for this time as well (I am assuming a modern Ford here), if you did such thing you want to be extremely careful and know exactly what you are doing and the implications as damaging this module is not something you will be thanking yourself for! I don't think a new module would work as it's most likely CAN BUS so unless your car is equipped with this?

Martin