button box assignment help

I have built a simple button box to operate my aircraft lights. I currently dont have fsuipc but will in the future. How do I assign my aircraft lights to the buttons? Obviously in the fsx controls section there is no taxi lights etc. I know I need to do something with the xml file but I am unsure how to do it.

In flightsim/options/settings/controls assign your button to do a keypress of 'L', that should toggle your lights on and off ok.

Cheers Gwyn