On jetmouse keygen v1.5 put the 10 digit gps unit id number (will be unlocked only in your gps)or the sd serial # (it will be unlocked in any gps you put the sd card
under-select map product --on the bottom ---custom map set---add the maps FID# also called mapid #
Click generate on the bottom-all those numbers will unlock the map--copy that 25 digit number into the gmapsupp.unl file --- don't add any enter --just 25 digits on the first line ----
on a sd card create a garmin directory--in that directory copy your gmapsupp.unl file (unlock file) and the gmapsupp.img
When you save the .UNL file in Notepad, be sure you set the "Save as type" to "All Files", not "Text Documents".
Copied from the link I gave you : i cant explain it better.