I am a bit struggling to get Knoppix to run out of my external hard drive.

My config is the following :

-Compaq Armada M700
-W2000 installed on the internal HDD. I don't want to have any change on that drive > That's my office stuff...
-I have an external HDD connected to the M700 with a USB2 connection
-I can boot the laptop either using the internal HDD, the CDROM, or the floppy.
Ultimately, my goal would be to insert a floppy with a bootloader, and then run Knoppix from the external HDD.

I am able to run Knoppix from the CD. The external HDD is well recognized, and mounted when I run from the CD.
I have tried to install Knoppix on the external HDD. Everything is fine until I restart using the floppy. Then I get a kernel panic. It seems that there is no USB support in the floppy.

Do I need to rebuild a kernel? I tried to understand the document about booting from a USB key, but the config is slightly different. I boot from a floppy, but must load the USB drivers to get access to the system, on SDA1....

Any help?