I would make following:
- search the layout of the us keyboard (qwerty.. probably this is what your distro installed).
- search the layout of the french keyboard (azerty..). here? http://en.wikipedia.org/wiki/AZERTY
- write down on a paper 2 columns with US on the left side and the corresponding FR on the right side
for all signs (/&%$§zy..)
then you have it...
Look at your list when you have to write your password.
This is what I am using when I install distros where they come usually with qwerty us (I have mostly qwertz de-latin1 at home).
Later, change the setups of your distro (or/and in extlinux! I made different setups in extlinux for changing the keyboard.. so far I remember this keyboard change setup were defined/indicated in the UBCD) for having the correct keyboard automatically.
But perhaps you prefer to keep the list?...;-)