password protected printer

I'd like to set up a printer on my work machine, to serve print jobs to our staff. I would like to have a username password combination for them to enter on our client machines in order to enable secure printing. Our staff work with clients who may attempt to print extremely large files, so I want to safegaurd that with a password. Is this possible? I've been googling and looking at apple support communities for over a week and can't find any helpful instructions.

I have bought the server application and installed it on my imac, where the printer is plugged in via usb cable. All computers are on the same wireless network. My iMac is running 10.8.2 the clients are on 10.6.8. All are up to date.

Thanks for any help.