Cannot Im****t prn extension files

I have an 2000 Access application that allows me to upload files created in
a 
..prn format. I recall that I needed to go into the HKey Local 
Machine\software\microsoft\jet\4.0\engines\text and add the prn to the 
existing list. I have done this on my new computer using XP and Office
2007 
and it gives me an error "You Cannot Im****t This File unless it is using
one 
of these extensions".
 Is there a way to work around this in Office 2007? I cannot change the
file 
extension.