Please remember that you use this software at your own risk.  Further details of usage in readme.txt

System Requirements

If you just download the shonkymaps.img file to copy directly into the /Garmin directory on your Garmin GPS device or SD Card then this page is irrelevent.

However if you want to do the full install into Basecamp or Mapsource then you need

- PC with running Garmin Mapsource or Basecamp

- Approx 406MB free Hard Drive Space

- A LICENSED version of Garmin "Trip and Waypoint Manager", "MapSource" , "CityNavigator" or "BaseCamp".  Some of these are available for download for free from the Garmin support site  
Some users have reportedly been able to use shonkymaps on other operating systems (such as Linux) using products like SendMap.  Refer to the gpsaustralia forum for details.