I had to use Knoppix for some recovery stuff on a Thinkpad R40e, and
it was hanging during boot (knoppix 3.7). These steps allowed me to
do this and get the data out on a USB memory stick:

- Boot using the 'failsafe' option WITHOUT the memory stick in place
- When knoppix comes up completely, start a shell window and become
root by doing 'su - root'
- Load the usbcore and usb-storage modules in order:

# insmod usbcore
# insmod usb-storage

- now insert your USB memory stick and load usb-ohci:

# insmod usb-ohci

The hard disk (that I was recovering from) was available as /dev/hda1
and could be mounted by

# mount /dev/hda1

and would then been available as /mnt/hda1

To make the USB stick available (seen as /dev/sda1 in my case), create
a directory and mount:

# mkdir /mnt/usb
# mount /dev/sda1 /mnt/usb

- Now, copy your stuff from /mnt/hda1/ to /mnt/usb and
umount when done:

# umount /mnt/usb