Here is the 4.5.10 GA 1575 French translation. No major changes in the language files (just one more error message).
As usual, you can download a package that will install these files for you plus the French spelling dictionary and the French date zimlet.
The package can be downloaded from Fichiers WHM
You will also find there a script "zmdict" that converts a list of words into a file suitable to be used as a dictionary extension, in case you need to add more words to the French dictionary (actually, it will work with any dictionary). The script explains how to do it.