printing black & white on a colour printer

[Levi Waldron <onemorenut@gmail.com>]

I am using CUPS with the hpijs driver to print on an HP Deskjet 710C,
on a Sarge/KDE workstation.  I am out of colour ink and don't intend
to replace it, as I only want to print in black & white.
Unfortunately,
 whenever I print something with colour, the colour portions come out
blank as it tries to use the non-existent ink.

I have tried:

 - Choosing "grayscale" from the options I get when sending a print
job from KDE apps.  This has no apparent effect.
 - Defining a Deskjet 600 non-colour printer to send print jobs to. 
There is no output when sending a job to this printer.

Thanks for any ideas.