Answer resided in article 'Headless knoppix' (docs division)

the line :

Code:
echo "knoppix:$PASSWORD" | chpasswd
does the trick.
Nevertheless you must be in root.
Since you can't sudo this with knoppix user ,you'll have to work with inbetween script.
The reason I use sh xxxx.sh is that I can use then from a remote drive. (I don't have to chmod it - since I can't either )

How I pulled it off :

- launch KWrite (or other editor)
type here :

Code:
echo "knoppix:testpassword" | chpasswd
save it as setmyknoppix.sh

- Now type in knoppix console :

Code:
sudo sh setmyknoppix.sh
Now the password for knoppix is set to testpassword

This can also be applied for the root .

- launch KWrite (or other editor)
type here :

Code:
echo "root:rootpassword" | chpasswd
save it as setmyroot.sh

- Now type in knoppix console :

Code:
sudo sh setmyroot.sh
et voilà ....

greetzzzz...