Lucent modems are common (infact I have one) and you should not have to install a driver for them. If your modem is PCI try this first.

Type this into a root shell:
cd /dev
./MAKEDEV ttyS4
ln -s ttyS4 modem
chmod 777 modem
chmod 777 ttyS4

This will set up your default modem to run on ttyS4. For Win/DOS users ttyS4 is com5. This is an unusual com that is sometimes used by PCI modems.

I can't help you with installing drivers because I have never had to do that. Knoppix has so much already included that it is just a matter of knowing how to use it. Hope that helps