(Yes, I know I'm a year late here.) If you can convince them to use some other editor instead of notepad (better try with some editor with very similar appearience and feel) you may be able to write a macro hook in it to check for the file being notified. You might not even have to do any programming, as some editors already check when saving if the modification date of the file is later then when it was opened, and warn the user about it. That of course might still fail if they save almost in the same moment, but you can get over that if the editor also locks the file at saving automatically (which is also not an unknown editor feature).

This also works partially if you can convince only some of the people, as it would still warn him if he saves the file when someone else have changed it since he's loaded it.

(Update: note that I've also updated my reply to the parent thread.)