Debian Etch - install us-keyboard driver

Hi,

i'm using a debian-4.0r1 on an old subnet machine.
I have to extend it with an other keyboard [United States Keyboard layout - cherry].
What i have is a DVD of etch 4.0r7.
How can i install and load the keyboard-driver for the us-keyboard?
Can anybody please give me a hint how to do that?

Thanks in advance