Simply copy the following text over into your existing \panel.1\panel.cfg file seen here;
(Notice, the marker lamps need to be moved over slightly from the original panel supplied with the airplane.)
You then move the files found in the \PA35_Gauges folder items into the \Gauges\PA35_Gauges folder that you should already have installed. This adds the needed .XML and .BMP files for your 2D & Virtual Cockpit instrument panels.
A successful installation? Push the provided "test button" and see if the lamps do indeed follow your test action.