I have also been unable to get my Canon i9900 USB printer working.
I
had assumed it was because there doesn't seem to be a driver for it out
of the box, but could be a bug in Cups.
I had no joy with a Canon ip4000 until installing 'gutenprint-cups',
restarting CUPS, and picking the gutenprint driver (which actually
listed the model - went to the 'admin' tab, and it was listed as a new
printer').
Worth a try...
Chris