I don't know when the Dnn 5 fr-FR language pack will be online on dnn.fr, it should be produced soon but i'm not part of the translation team. I've personnaly planned to start working with Dnn 5 on middle-february ; you may know that we - part of french team - are actually making a new website in order to distribute articles and language pack, and it takes all my free time. So, I don't really know how to install the language pack if process has been totally rewrited in Dnn 5, but you may want to try this :
- Copy the zipped language pack in the folder /Install/Language/,
- Call your website using the following URL : http : // yourURL . com / Install/Install.aspx?Mode=InstallResources.
It works on dnn 3-4, it may work on 5.
In all case, it seems that you can without any problem install the Dnn 4 language pack on Dnn 5, then install the new one when released.
Hope it helps