Hi

Jetmouse keygen is a brilliant tool, just a bit tricky to understand for some folks.
1. Launch the keygen, and type in your 10# (10 digit decimal) SD-Card ID into the "Unit ID" field.
2. Select "Garmin Mobile XT" or "Garmin Mobile PC" in the Software Product drop-down box and hit the Generate button below the “Select Software Product” field.
This will be the software unlock code, this is the code for the SD-Card you are using. Save the code as SW.UNL in the Garmin Directory of your SD-Card
3. Now enter your 10# (10 digit decimal) GPS Unit ID into the "Unit ID" field.
4. Select "Garmin Mobile XT" or "Garmin Mobile PC" in the Sotware Product drop-down box.
5. Select your Map Product in the drop-down box and hit Generate button below the “Select Map Product” field
This will be the map unlock code, this is the code is for the map you are using.
Save the code as GMAPSUPP.UNL (or whatever else you named your map, eg. FILENAME.UNL) in the Garmin Directory of your SD-Card.
Copy your Map as GMAPSUPP.IMG (or whatever else you named your map, eg. FILENAME.IMG) to the garmin directory and of you go.

If this is still to difficult just download UnlockGarminMaps.7z (also called GarminUnlocker).
Follow the instructions in the readme file and you don't have to mess around with any codes anymore.
Has work for me with any map I am using. I am using GPSMAP 78, MobilePC, MapSource and HomePort.

Hope this will help