Hard way, I'm afraid. That is, choice of paralleling your track with catenary spline(s) or replacing the track with a track asset which includes the overhead, then adding support structure (which, ideally, should consist of trackside objects). Trolley wire is not too hard using the second method; I made a half-donkey'd system of catenary in TS2009 but it results in curves without pull-offs and doesn't produce actual catenary curves in the vertical plane.