gnome live cd - belgian keyboard layout

Hello,

Is it possible to choose the belgian keyboard layout during boot as a
cheatcode ?
What is the exact sentence I would have to type ?

Or is it done after the cd is started, in the terminal ? What is the
exact sentence then ? Do I have to be logged in as root or su ?
Or can I choose the keyboard layout in the graphical environment?

Thank you very much for your answer

Ghislaine De Vos