Do you already have grub on your computer?

If so here is an example from my Libranet /boot/grub/menu.lst file
(snip)
title Debian GNU/Linux, kernel 2.4.18
root (hd0,6)
kernel /boot/vmlinuz-2.4.18 root=/dev/hda7 ro hdd=scsi hdc=scsi
savedefault

Note: grub uses it's own syntax for your hd look at the root entry, my root device is /dev/hda7 note grub calls that hd0,6. For a knoppix install your kernel entry will be /boot/vmlinuz-2.4.20-xfs the hdd=scsi and hdc=scsi entries are for scsi emulation of my cd-rom and cd-rw.

HTH

rock