1- Place the maps (.jpg) in a folder you like. Can also be a web place (url).
2- Edit the .kml files and put the path/folder you used before. Pay attention to "/", not "\"!
3- Now import (drag & drop to Places) the .kmls to GoogleEarth. I put them in a separate folder named MySat Overlays.
Actual view of the sat images is "Eye at 1.79 km". You may go down to 1 km. Bellow this the quality suffers...