Plug the device in and then type 'dmesg' in a terminal. Somewhere near the very bottom of the output it'll mention a device node, like /dev/sda or something. Then you just mount a partition off that, etc:
Code:
mount -t vfat -o umask=000 /dev/sda1 /mnt/usb
Check out 'man mount' to find out all the details but that should get you started