edit /etc/init.d/mountkernfs.sh

change the following line

domount usbfs usbdevfs /proc/bus/usb usbfs -onodev,noexec,nosuid

to

domount usbfs usbdevfs /proc/bus/usb usbfs -onodev,noexec,nosuid,devgid=46,devmode=664

i chose group id 46 (the plugdev group) because it made the most sense to me.
users who can plug devices into the system should have the permissions to read
and write them.  you can chose another group if you would like, just get there
corresponding group id from /etc/group.