As indicate on the txt files include in the package, you have to copy the file into Garmin/POI folders in your memory card or directly on your phone (e.g. : N95)
Then you have to use the **** to generate the unlock code (you need your Garmin XT/GPS ID - the MAPID is 900) and to past it in a notepad file (txt) that you will named : mpfulleurope.unl. Then you place this file in the same folder than the .gpi file.

As I already said, all this explication is in the readme file include in the archive and it's certainly better understandable than my own explication