There are two ways - one can be setup so that any and all geometry is dynamically exported to native.
I'd have to do some research to find where that is. Maybe someone else can add that information.
To manually do it, in the General Geometry task/tools, the second icon is export to native. When selected, it asks you to select the civil elements. I assume at that point it offers a dialog box to save the geometry as an ALG file.
Since you are using the InRoads version, there should be a ton of videos on Plan and Profile Generator and many other things as well.
Good luck.