Changing keyboard layout when netbooting linux mint (And other debian variants)

When you boot the Linux Mint live cd to have a live recovery system (described here), then you have the default english/us keyboard active.
That's inconvinient when your keyboard has a different layout.

You can change it to the one you use by adding this to the APPEND statement in your boot configuration:

 locale=de_CH console-setup/layoutcode=ch

With these two setting, you receive most messages in german and the keyboard is set to swiss german.
The layout is correct in the X-Window system and in the terminals inside X.
On the console (Switch with CTRL+ALT+F1..F6) you will still have the us keyboard, if anyone has a tip...