Over 2 weeks explain to your unit what geocaching is what is involved (see fact sheet in files). If you use a coin or bug then you could use it to create a link with another colony in another country.
Small container (must be weather proof) or one for each lodge. note book for cache log book, pen, small items to put in the cache possibly a World scout geocoin (available from scouts.org.uk/shop) or travel bug, a clever place to hide your cache and an account at geocaching.com
Handheld GPS for each group (or GPS enabled phone if seeking real geocaches)
To log a cache you must first become a member of Geocache which is free then follow all the guidelines on the Geocache website (geocaching.com).
However, you can set up a small course of pretend geocaches and enter their locations on the GPS as waypoints and show Cubs how to use a GPS to enter waypoints, select a waypoint and instruct the GPS to point you to the geocache.
When nearing the cache remind the young people of the cache name, any instructions or hints and to search carefully, leaving no trace of their hunt, and to watch out for muggles!
Make sure the cache log is signed and replace exactly as found. In a simiulated trail you can leave clue letters in the caches that the Young People need to note.