You can add the ERR MiniCommander EX to control the dummy unit. The MSRP is only $35, and I think you can get a bit of a discount with Boxcar Bill on the forum here.
From the ERR Web Site
The Mini Commander EX has a full complement of outputs for supporting dummy engine applications. Outputs feature support for directional lighting, coil couplers, ditch lights, and a re-configurable output for strobe, smoke, or cab lighting. Additionally, serial signals are output for sound systems.