From Nicolas Burrus Homepage

Misc: Printing Booklets on Linux

• Configure your printer as recto/vecto on short edge
• Use the following script, assuming that the printer name is Canon:

#!/bin/sh

PRINTER=Canon

if test $# -ne 1; then
    echo "Usage: $0 document.ps"
    exit 1
fi

if test ! -f "$1"; then
    echo "$1 does not exist."
    exit 1
fi

< "$1" psbook | psnup -2 | lpr -P$PRINTER