I usually do most of my work as root but I think this might work to make a ext3 partition writable by anybody, including of course the user knoppix. Either do these codes in the root shell, or use sudo, as in the example below:
Code:
sudo mount /dev/hda1 /media/hda1
sudo chmod 777 /media/hda1
This will make the whole hda1 partition writable by anybody.
I hope it works for you. Regards.