Configuring the "Microsoft Ergonomic Natural Keyboard 4000" under Debian 5 Lenny

In order that they USB keyboard works in the GRUB screen, enable from the bios setup the
"Legacy USB keyboard support" option

Install the unstable package xkb-data_1.5-2_all.deb

In the kcontrol (control center) -> keyboard layout: activate the keyboard model "Microsoft Natural Wireless Ergonomic Keyboard 7000".

And voila!

If you want to test the keys use the
$ xev
command, and run
$ modmap -pke
in order to see all the keycode associations.

I also changed my /etc/X11/xorg.conf to
Section "InputDevice"
Identifier "Generic Keyboard"
Driver "kbd"
Option "XkbRules" "xorg"
Option "XkbModel" "microsoft7000"
Option "XkbLayout" "latam"
EndSection