All you have to do is create 1 little piece in the OC, something like this:
Although thats a rough one that I just threw together as an example.
Then you take that object, load it into the construction kit as the crossties of a model, set the number of spines to 2 and set their desired thickness and y-axis values, and set the number of rails to 0. Then export your model as a 3ds, import it to NL, ?????, profit.