if the application is not able to send mIRC any indication of having written to the file (incorporating a DLL that triggers events or otherwise) then you'll have to poll the file periodically to check if it's changed. there are several ways of detecting a change in a file, an efficient method being to compare $file().mtime to see if the value returned differs from what it was previously. of course, a change there might not necessarily imply a change in the file's contents, it's possible that an external process wrote to the file and then removed what it wrote. this might not apply to your case in particular, but it's something worth considering in general
other checks involve examining the data that makes up the file, such as comparing $crc() or $md5() before and after results, but these run slower than checking $file().mtime which might be a crucial distinction if you plan to perform this check every second or so.
