It is possible to do the routing with xRouting (or a patched xRouting) and make it possible to work with Babel. Do you want to have the same content on be/fr and fr/fr? This will be a bit more difficult.
Use this description and change the base url according to /be/fr/ and so on. If the routing does not detect the right context, xRouting has to be patched a bit (this can be debugged with the system setting xrouting.debug=1 and ?xrouting_debug=1 as suffix in the url).
Alrigty, so if I am geting this right my context keys wil be something like befr and benl, the base urls be/fr/ and be/nl/ and the site urls domain/be/fr/ and domain/be/nl/.
I have been using Xrouting before so if this is going to work that will be great. I will give it a go!