Mount your cdrom, cd into KNOPPIX and do this:

dd if=boot.img of=/dev/fd0

If you need to format your floppy first:

fdformat /dev/fd0H1440

I was just looking at the docs and this isn't in there is it? Glad I wasn't an ass w/ RTFM!

Actually tho- I see that you did and I would highly recommend getting yourself acquainted with Smart Boot Manger as the docs suggest. It's great to have on a machine that won't boot from cdrom. Just my .02.