First success.

The driver in the current Knoppix distribution seems to be the sourceforge
one, which has KNOWN problems with usb-uhci.

Quote from the 'readme'
There is a serious "conflict" with the usb-uhci driver and atmel's board
which leads to one problem. The system hangs :( .....

This never happens with the uhci driver.
But on my boot, the usb-uhci driver is loaded.

What I did (in short):

- got the better driver from
http://at76c503a.berlios.de/
- compiled it (no problems)
- made /lib writable (in ramdisk)
- removed all old driver files in /lib/*
- installed the new driver
- plugged in the Atmel device

Voiala, Knoppix remains stable running,
'hotplug' did it's job, 'lsusb' reports the driver, iwconfig is usable.

Details will follow.

Thanks to all people making Knoppix available!

best regards

Georg