Yes you should be able to use the USB drive in text mode. With the power off, insert the USB data device into the USB port. Next boot off of Knoppix with the boot prompt
It will boot up & get you to a command prompt. USB devices shouls be detected as either /dev/sda or /dev/sdb. In order to copy data from the hard drive to the USB device you will first need to mount both devices. For the C: drive use the following.
knoppix 2 vga=normal
Then check if you can see the C: drive's filesFor the USB drive use
mount -t vfat /dev/hda1 /mnt/hda1
See if you can write to the USB device
mount -t vfat /dev/sda1 /mnt/sda1
If this is successful then you can now begin copying file from the C: drive to the USB device.
touch /mnt/sda1/testfile && ls /mnt/sda1
I hope this helps.
cp -v /mnt/hda1/autoexec.bat /mnt/sda1/