I want to return to *nix.- modem config

I found a link to http://www.pla.net.py/home/oliver/3com.html which told me
to:
"setserial /dev/ttyS? irq# portI/OADDRESS ^fourport ^auto_irq skip_test
autoconfig spd_vhi "
which gave the response :
"Cannot set serial info: Address already in use."
How do I free the address?
I have a US Robotics V92
I am running knoppix from the HD
Am I on the right track?