Comment 5 for bug 93573

I'm sorry, please ignore the above statement.
Apart from the fact, that it doesn't seem to be very intelligent to randomly copy driver-files, it only worked till the next boot.

Working solution: I backed up and deleted /lib/modules/2.6.20-16-386/kernel/ubuntu/wireless/acx/acx.ko, so that my self-compiled driver in /lib/modules/2.6.20-16-386/extra/acx.ko was loaded.
The new problem was, that the firmware "tiacx100usbc0D" wasn't found. Of course not, because there is no firmware with that name in the restricted-modules-package. I found the firmware here: http://195.66.192.167/linux/acx_patches/fw/acx100_1.0.9-USB/ and copied it into /lib/firmware/2.6.20-16-386/acx/1.0.9 and created a link to it in /lib/firmware/2.6.20-16-386/acx/default. But it wasn't found. Final solution: I copied tiacx100usbc0D in /lib/firmware/ and it finally works.