Use metrostroi_trackeditor command and metrostroi_trackeditor_* console commands to record track paths (you need to tell the lua code where railroad is by moving a train over all driveable sections.

Ok, I've recorded the path creating the red line, placed signals, but it still says "No ARS Frequency". Do the signals need to be placed before or after recording the path? Or does each signal need to be spaced out a certain amount? Or maybe this just isn't perfected yet. Either way this is still a really cool mod.

Edit: Got it working. Don't know if it was because I restarted, or that there was an update earlier today, but it's working now. Thanks for your help and for an awesome mod.