Duplex printing w CUPS and HP Office Jet?

[forkandwait]

CUPS seemed to magically work for me recently, and I have basic printing set up, but I would like to make the printer default to double sided. I can't find a button to push on the local CUPS admin webpage. Does anyone have an idea where it is, or do I need to edit a config file?

Here is my basic info:

Description: HP Officejet Pro 8500 A910
Location:
Driver: HP OfficeJet Foomatic/hpijs (recommended) (grayscale, 2-sided printing)
Connection: socket://192.168.1.3:9100
Defaults: job-sheets=none, none media=na_letter_8.5x11in sides=one-sided

 

[tingo]

I think I used the $ lpoptions command for that (the CUPS one).