Check out this site:
http://christophe.delord.free.fr/en/adsl/debian.html

I've downloaded the script and tried it and successfully use the speedtouch 330 USB to logon to internet.
Also you need to download this firmware file from speedtouch.com SpeedTouch330_firmware_3012.zip as mentioned in the site. Put both files together in the same directory, for example /home/knoppix/speedtouch/
The only thing you need is the VPI and VCI, together with login username and password. VPI and VCI
can be found by googling e.g. http://www.eicon.com/support/helpweb...l_settings.asp or from your service provider,
Login :
Password :
VPI : 0
VCI : 38

Only other thing is when booting up linux, try to unplug the modem from USB port, only plug it in after bootup, otherwise the modem won't work.