If you want to write to folders, redirect them to your hard disk - see my post on cd-based knoppis as webserver (http://www.knoppix.net/forum/viewtop...=7296&start=10).
The main points are: -
make a home directory on your hard disk;
create the directories you need on it;
link them to your cd-based directories.
You can write a batch file to do the work for you with the command for each folder to link
sudo cp -fs /home/knoppix/your_hard_disk_folder /your_cd_based_folder

Dave