What you need to do is to create an activity and create a player path that has a start point of whereever you want (you can just find the spot, right-click and choose "Place start point"). Set the name to whatever you want (I usually use the station name and track number), set an activity description and briefing (it can be whatever text you want) and save. Now you should see the new point as a start point in the Explore Route mode.
(I can post more detailed instructions on Sunday night, if you're not sure how to create a path and/or set a start point.)
Overheard in NY Penn: "All aboard! Get on the train if you're coming with us!"