Can be a little difficult but i got it working on mine with Africa Maps
1. Download and install Garmin Mobile XT.
Link to the installer:www8.garmin.com/software/GarminMobileXTforWindowsMobile_42030w.exe
2. Extract the archive to your storage card.
3. Insert your storage card into your PPC, when prompted, install the application.
4. Launch GMXT, got to Settings -> About.
5. Make note of your "Card ID"
6. Install Maps via Mapsource
there are 'other' options available which i'm sure you can find