It is easy once you know how to program.

First, you will have to wire the red wires to common or positive.  Second there are Aux outputs that can be programmed to cycle not only two color but three colors of class lights also.

I do not know which Aux outputs they are and I do not know how to program them.  If no one here can do it (doubtful), then there is both an ESU Google forum and an ESU Facebook page that will be able to give you details quickly.  I also think that Christian Javier published in this forum how to do it or referred to a YouTube video that he did.  He cycled through different lights but the outcome would be the same.

"marker lights"

I never understand why manufacturers put red and green in "marker lights" on a locomotive (which are actually not marker lights, but classification lights).  95% of the time, the lights will be either off or white, 99% of the time for a low horsepower hood unit. 

Lights

I think the proper name confusion comes from the fact that some locos, like Alco RS3's and the earlier mentioned H16-44's, don't have class lights built into the hood ends like EMD's, but use seperately mounted lights that "look" like caboose marker lights. So most people, as Dave points out, name them incorrectly.

Mike in Florida.

Thanks Nick.  Christian may

Thanks Nick.  Christian may have installed common Anode LEDs.  I'd have to ask.  The original Atlas decoder came with 3 pads for each light and then the colors cycled through with repeated pushes of 2.   Too difficult for me to try and figure that out on Loksound.  Instead, it appears that there's enough room for both decoders.  So I bridge the track wires up to the Atlas decoder laying on top of the ESU (separated by tape) and use that for class lights only.

To Dave's point....yes, for this particular loco it's confusing.  I think in this case they seem to just be marker lights since Red is called a marker light and no white was provided.. so I'm calling green a front marker.

"Front Marker"

That's... not how lights are used on locomotives. A green light on the lead engine actually means something, and it's not "front of train" (unless you REEEEEEEEEEALLY stretch your definition).

Red Markers on Locomotives

Admittedly not as common, but engines being used as rear pushers or commuter engines in "push-pull" service would show red markers. And since on locomotives with built-in class lights and marker lights had them in the same place, the distinction gets a little confused to railfans and modelers. (See a lot of Canadian built engines that had individual white/green/red classification & marker lights mounted above the number boards.)

(To be clear I'm not disagreeing in any way with your statement. White is definitely the most common, green is more rare but still used, but red is specific to only those situations - although if that's what you're modeling then red markers would be most common FOR YOU. But 95% of the time it should be white.)

Red

Agree that in general it’s not so common, but I see red markers all the time around here on commuter rail.  All the commuter rail trains operate with the engine on the outbound end of the train, so when they’re pulled into the stub ended stations in Boston the engine is not next to the station itself.  Running outbound, the engine marker lights are off, and the markers on the end of the cab car are lit red.  Running inbound the engine marker lights are lit red, and the cab car marker lights are off.