I'll give you some general info, as I don't have a knoppix hd install

Place a zip disk in your zip drive and open a terninal or console as root and type this command:
modprobe ppa
if you did not recieve an error message and saw info saying something about your zip drive and partition /dev/sda4, then you need to use the ppa module.
If modprobe ppa gave you an error then use this command:
modprobe imm
now you should see some info regarding your zip drive, so you need the imm module.

So to make this work at boot up, the easiest way is to edit the file: /etc/init.d/bootmisc.sh
and at the end of bootmisc.sh add the corresponding modprobe command above that worked, and save bootmisc.sh. (be careful not to mess up bootmisc.sh)

The second thing you will need to do is (again as root) edit your /etc/fstab file and add a line corresponding to your zip drive, I use the following line:
/dev/sda4 /zip vfat defaults,user,exec 0 0

The next thing (as root) is make the mountpoint:
mkdir /zip

Then finally as your username (in KDE) right click on your desktop and "Create New" - "floppy device" you can click on the icon and choose a zip icon instead of the floppy icon, select the device tab and from the drop down select "/dev/sda4 (/zip)" also select the unmounted zip icon and you should have it.

~rock