Postscript printing and FinePrint

Greetings,
I converted a LaserJet 2100M to CUPS, switching from PCL to Postscript 
in the process (the printer has Postscript, it was just being ignored) 
and I am having a problem with FinePrint and duplex printing.

FinePrint emulated duplex printing (the 2100M has no duplex installed)
by printing odd pages, "locking" the printer somehow, and requiring
the operator to confirm a dialog *and* walk to the printer, collect
the half-printed pages, put them back in the tray for the next pass,
and push a button on the printer. This way, intervening print jobs
would not interfere.

What I don't know is whether this was (a) a feature of the Windows 
spooler (how do I replicate it with CUPS) or (b) a feature of PCL (how 
do I replicate it with Postscript, possibly using a PPD) ...

Thank you for your consideration,
Davide Bolcioni
-- 
There is no place like /home.