In order to enable USB devices in VirtualBox under Debian Etch first determin the group number of the VirtualBox group (vboxusers). This can be done at the terminal by typing:
cat /etc/group | grep vboxusers
The output should look like this:
vboxusers:x:####:systemuser
Where #### is the group number.
With the group number in hand simply edit the /etc/init.d/mountkernfs.sh:
nano /etc/init.d/mountkernfs.sh
The above terminal command should be done as root or using the gui (Gnome):
gksu gedit /etc/init.d/mountkernfs.sh
Then change the line that reads:
domount usbfs usbdevfs /proc/bus/usb usbfs -onodev,noexec,nosuid
to:
domount usbfs usbdevfs /proc/bus/usb usbfs -onodev,noexec,nosuid,devgid=####,devmode=0664
where #### is the vboxusers group number.
Reboot and usb access will be enabled in VirtualBox.