A trick I did with a p2k sw9 that I wanted to operate with a decoder, but had severely limited space for the installation, was to power the locomotive motor only with the decoder. I left powered the lights directly with track voltage so that both are on all the time. The sw9 did not have a lighting package as yourE6 does, so you would have to take the power to the lighting board from the track, not directly to the lights. You would probably want to use a small resistor in series to drop the voltage to the lighting module from the 14 volt track voltage that dcc uses to 11 or 12 volts to preserve lamp life. If you do that, the lights will be lit any time the track is powered up that the locomotive sits on.
