My Pi is running headless, so I can't test this, but first have a [look at this page][1]. Then try if you can set the keymap from a terminal:

    setxkbmap fr

This should switch to french azerty layout. You can put this command into your `~/.xinitrc` if it works. There are also many other keyboard layouts available (like `be` for Belgian azerty). 

**Edit**: If you want to make this permanent, you need to make sure the `~/.xinitrc` still starts the default WM and desktop. So put these lines into your `~/.xinitrc`, if it does not exist yet:

    setxkbmap fr
    . /etc/X11/xinit/xinitrc

This will run the default xinit script after setting up the keyboard layout.

  [1]: http://wiki.lxde.org/en/Change_keyboard_layouts