Psychoholic,
there is a section on this in the sane documentation on
http://www.mostang.com/sane/man/sane-usb.5.html.
I'll paste it here for you. I think it can solve your problem.
Guust
Libusb can only access your scanner if it's not claimed by
the kernel scanner driver. If you want to use libusb,
unload the kernel driver (e.g. rmmod scanner under Linux)
or disable the driver when compiling a new kernel. For
Linux, your kernel needs support for the USB filesystem
(usbfs). For kernels older than 2.4.19, replace "usbfs"
with "usbdevfs" because the name has changed. This
filesystem must be mounted. That's done automatically at
boot time, if /etc/fstab contains a line like this:
none /proc/bus/usb usbfs defaults 0 0
The permissions for the device files used by libusb must
be adjusted for user access. Otherwise only root can use
SANE devices. For Linux, the devices are located in
/proc/bus/usb/. There are directories named e.g. "001"
(the bus name) containing files "001", "002" etc. (the
device files). The right device files can be found out by
running scanimage -L as root. Setting permissions with
"chmod" is not permanent, however. They will be resetted
after reboot or replugging the scanner. It's also possible
to mount the usbfs with the option "devmode=0666", e.g. by
using the following line in /etc/fstab:
none /proc/bus/usb usbfs defaults,devmode=0666 0
0
However, this way everyone has access to all USB devices.
Another way to set permissions is to use the hotplug util-
ities (
http://linux-hotplug.sourceforge.net/), which sup-
port dynamic setting of access permissions. Last, the
frontends can be run as root. However, that's not recom-
mended for security reasons.
PS: use mount -a to mount your filesystems after you made changes to /etc/fstab.