Hey,
I'm pretty new to knoppix and debian so whatever I tell you theirs likely to be a better way. (Dont want to be the blind leading the blind!)

Im at work and I don't have a knoppix Cd at the moment ...
(stephen actually answered this question for me which is why I know.)

If you "man update-modules" it tells you the name of the file that is used in deb to make the modules.conf.

(In RH based systems this doesn't exist)
the Deb way is way better...but its new to me.

What I did is do a lsmod BEFORE i got it working. (i.e. lsmod > modules.before)
Then use the netcardconfig - this is really smart and if it finds a wifi card it automatically starts wlcardconfig. (I was VERY IMPRESSED by this!)

Presuming it all works you can go ahead and do another lsmod (lsmod>modules.after) then find all the modules that were loaded.

Then work out and they go in the file which is refered to by man update-modules

Then you run update-modules and it rebuilds it and next time you start up you'll have the modules loaded.

If you wanna auto set the Wifi params then a simple shell script... (the exact commands escape me right now so this is just an example)
#!/usr/bin/bash
# set the wlan stuff for bootup
wlanconfig eth0 essid = "mywifi"
wlanconfig eth0 channel = "11"
wlanconfig eth0 ..... etc

stick this in /etc/init.d and call it something like setwlan
then in rc3.d (depending where you wanna start it) create a symlink
S80setwlan -> ../init.d/setwlan (use ln -s)
repeat in rc4.d and rc5.d

S80 is a guess, it needs to be AFTER networking....i.e a bigger number else eth0 won't exist!

If I remember you also need to create an alias in the modules
something like
alias eth0 <name of driver>