Draft mode for HP Color Laserjet 2600n to save toner

How do I get the HP Color Laserjet 2600n to use less toner?

There is a selectable 600dpi mode, but I don't think it affects toner
use rate much, if at all.

We use the printer for Community Association paperwork. Occasionally
we need really bright hi-res professional paperwork (brochures,
artwork, maps, etc.), but most of the time we just need cheap
(letters, memos, etc.).

Overall the thing works great. I would just like to find some way to
use less toner for the 80% of the time we only need draft-quality
printing.

Thanks for any help,

mel