I had a problem in http://localhost:631 of being asked at the end of Add a Printer for a user name and password for a network printer which requires no password.

I am not sure if the printer was asking for the password, or the setup program. I tried root and the root password, and some others, with no acceptance. The printer was not added.

I notice that if you use the Firefox browser on the N900, select a location, then click "print this map", it will give you a screen to select a printer (no good for me, since I don't have one added yet).