🚀 go-pugleaf

hello.  we have an HP laserjet IIIsi, which (as you may know)
is capable of printing on both sides (duplex).  

when we print multiple page documents (like from a word
processor) in postscript, with duplex on (on printer), we
get duplex... fine.  HOWEVER, i am curious if anyone knows of
a postscript trick (or other trick) to force the HP to take
every 2 pages it gets and place them on obverse/reverse of
one piece of paper.  in particular, i am interested in printing
from a mac using canvas.  canvas, by the way, does allow you
to make multiple page poster-sized documents, but the printer
still prints one side per page  (even tho it is all one job).

is there postscript code to add/remove to/from the file
if i print to a file, which would make it stop putting one
side per one piece of paper?   any ideas would be great!
email or post here.  either is fine... THANKS
jon    kca@caen.engin.umich.edu