For simple setup,
- Make a room as per documentation
- Assign live_blank_room / live_blank_object in obj_gmlive's Create
- Assign live_room_updated there as well, use the example script (which does room_goto_live)
- Do room_set_live for room(s) of interest there too
- At this point, when running the game with server connected, modifying and saving room will cause the game to transit to it's updated version