If the map is locked in Mapsource use Jetmouse keygen and read
[Only registered and activated users can see links. ]
There are screens show where to put the unlock code

The file Mapsource sends to your gps is an .img, it should be in a Garmin folder,if it's locked, download the linked gimgunlock, attach the gps to your pc, browse to that topo france gmapsupp.img, drag&drop the .img from gps in gimgunlock icon you have downloaded.