Hello,
It is not possible with advanced file I/O LabVIEW VIs.
There is a possible workaround by using low level Windows functions in a dll.
Perhaps the easier would be to set your properties at the top of your file.
You will find some explanations here :
http://forums.ni.com/ni/board/message?board.id=170&message.id=85101&requireLogin=False
regards
Marc L.
NIF