Is it possible, with DirectoryOpus, to automatically perform an action when a file is created/changed/deleted in a specific directory?
Opus doesn't have this capability but I have seen a standalone directory monitor/watcher tools which will do it. I'm not sure which to recommend as I've never used them but I remember seeing them on a few freeware/shareware sites.
If you need to run Opus functions on filesystem events then you can make the standalone tools call Opus via
dopusrt.exe /cmd command you want to run