Hi gjmontagner,
Sorry for the delay, still catching up after NIWeek. What printer do you intend on using with the cRIO (just so I have a reference). I can run through the setup I did previously for working with the network printer here in the office (a Ricoh Aficio copier/scanner/printer) and post the results of that, and some of that will be useful, but you will likely need to make some adjustments.
When attempting to add a printer, it's looking for the root, so you will need to add a password to the root user (using the admin user, both users are effectively the same-ish, both UID 0, but they use different authentication mechanisms). Try providing the admin login credentials and, if that doesn't work, login as admin and use the command passwd root to add a password for the root user, and try again with those credentials.
Basically, the "drivers" for printers on Linux come down to one or more .ppd files that describe to cups how to interact with your printer. When I setup the printer on my controller, I used the .ppd files that came with the foomatic packages (which cover a lot of printers). Check to see if your printer is already included in the set that comes with those packages and, if not, you really only need to extract out from those .rpm/.deb files (using file-roller, e.g.) the .ppd files and place them somewhere sane (e.g. /usr/share/cups/model).
I'll do a quick writeup on what I did to setup the printer here
