I know this is a somewhat late post to this thread, but this does sound like a useful function.
Windows itself provides watching functionality, so:
/filewatch C:\Temp\ignore.txt
would only need to add that file to Windows own watching functionality - it would not need to periodically check timestamps or CRCs.
If windows reports a file change, then it could trigger an ON FILECHANGE event.
ON *:filechange:mask: commands
where mask is (like other such events) a way of making only certain filespec's trigger the event (like e.g. *.txt)
