Comment 50 for bug 420015

In fact, it needs to run later than 50-udev-default.rules, so try adding the rule to /etc/udev/rules.d/70-cups.rules

And it should look like this:

ACTION=="add", SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ATTR{bInterfaceClass}=="07", ATTR{bInterfaceSubClass}=="01", GROUP="lp", MODE="660"