Ping, i suppose the most basic thing here to begin with is to have an event which must fire to notify automatically whenever there's a new file added to the directory. Now if this directory is not part of the thingworx repository the event, that should fire to notify change/update, should fire on the OS's file system.
If you are working on Windows you can check the IO.FileSystemWatcher class which can be invoked from powershell(includes the sample) and then you can do a HTTP POST to ThingWorx with the file for processing
If you are on Linux it'll be inotify
hope this helps.