well, I'm afraid you didn't just hit the wrong category, you possibly got forum of the wrong simulator as well. Since you mentioned lights_constfile, I'm asuming you're talking about OMSI? If yes, it's the wrong simulator, but you will need to edit an *.osc, I guess lights.osc. But again, that's not the right forum.
However if you want to build a bus for LOTUS, you will need to start from scratch due to the new container-architecture. It isn't possible to modify small details like this without the original author providing a module slot yet.