Printing duplex & 2 pages per side of each sheet

[Torquil Macdonald <torquil@frisurf.no>]

I have tried the following commands

 'mpage -2 -P- file.ps > outfile.ps'

 'psnup -2 file.ps outfile.ps'

'psnup -2 -c file.ps outfile.ps'

They all give me 2 pages of the original document on each side of the sheet of 
paper, but everything is upside down on the back of the sheet. The resulting 
document behaves like those big calendars, I have to turn the pages upwards, 
when I really want it to be like a book and turn them sideways. When I open 
up the document, I want there to be 4 pages from the original document next 
to each other.

Does anybody know what to do? I could solve my problem by rotating every even 
page in outfile.ps 180 degrees, but I don't know how to do that.