Ok that is fairly simple. It will involve a timer that checks if the file has changed, so it will only check so often.

Code:
;Start timer when mirc starts that checks for changes every 30 seconds
on *:start: .timerdayzprofile 0 30 dayzprofile

;Alias that checks if the file has changed and messages channel. Make sure to update the path for the file and the channel name to message to.
alias dayzprofile {
  set -l %filepath dayzprofile.txt
  if ($file(%filepath).mtime != %dayzprofile) {
    set %dayzprofile $file(%filepath).mtime
    msg #pball !editcmd !server $remove($read(%filepath,w,LastMPServer=*),LastMPServer=)
  }
}

http://scripting.pball.win
My personal site with some scripts I've released.