@mootze
Unlocked IMG file can be used directly with just copying the file to the Garmin directory. Rename to what's appropriate (gmapprom.img, gmapprom1.img, gmapsupp.img, gmapsup2.img) if you want more than one map in the unit or on the memory card. Make sure you don't overwrite anything you want to keep.
If two maps are covering the same area you will see the map with the highest priority value. One can use [Only registered and activated users can see links. Click Here To Register...] to examine IMG files.