If you are looking for how to do geo targeting using webmaster tool, then http://googlewebmastercentral.blogspot.com/2008/04/where-in-world-is-your-site.html If you are looking for code at Google API to do geo targeting then http://code.google.com/apis/adwords/docs/developer/GeoTarget.html
I think the OP means geotargeting, i.e. telling Google to associate a site with a particular country, as opposed to geolocation, which is something completely different.