Fedora Installation :: Enable Usb Support Virtualbox Fedora10

trying to understand the two underlined sentences below I got to ask Step by step. I created a new group called usb. I inserted a usb printer and scanner. I tried to find the file usbfs and there is where get stuck already. I only can find a folder with that name. The sentence (3 -) makes almost no sense to me.

a) modify file /etc/fstab clear open terminal, go to etc, su gedit fstab

b) inserting a line yes I understand that!

c) the right path and the number corresponding the "usb" group :

none /sys/bus/usb/drivers usbfs devgid=503,devmode=664 0 0

2 - locate file usbfs: in my case is /sys/bus/usb/drivers (I suggest to find the file with a usb device inserted;

3 - modify file /etc/fstab inserting a line containing the right path and the number corresponding the "usb" group :

none /sys/bus/usb/drivers usbfs devgid=503,devmode=664 0 0