Load Country Flag From Geonames API using JSONP technique

This Request.JSON http://mootools.net/demos/?demo=Request.JSON using JSON data in a way like this,

var data = {"previews":[
  {"Countrycode":"us", "src":"us.jpg", "description":"desc will be here"},
  {"Countrycode":"uk", "src":"uk.jpg", "description":"desc will be here"},
]};

In the above method we use Countrycode & images by writing name of each image our self.

I'm looking for a method to use Geonames via http://api.geonames.org/export/geonamesData.js?username=orakzai to retrieve Countrycode and CountryFlags via http://www.geonames.org/flags/x/xx.gif where xx is 2 letter ISO country code