Filetype creator & type

[Tim]

Hi,

I'm trying to change the file's creator & type by using the "filetype"
property, but I've noticed that it can do so ONLY when you create a file
with Open File command. As a workaround is it possible to get the contents
of a given file, delete the file, create a new file with Open File command,
change its creator & file type, and finally put the contents back in? I know
I could do this with a simple text file, but what about other file types?
BTW I'm doing this on OS X.

TIA
-- 
Tim