The alcohol should be something with flavour - a good port, sherry, Marsala, Muscat, rum, brandy, schnapps, or a mixture ..
Every two weeks, for twelve weeks, unwrap and douse with 1-2 oz alcohol, depending on cake size and thickness. After that time, any additional alcohol does not add to the fruitcake flavour. It is fully loaded and ready to go.
I'm currently dousing my Christmas cake with butterscotch schnapps - last year was marsala ..