code: function(lonlat) {
          var res = this.ovmap.getResolution();
          var extent = this.ovmap.getExtent();
          if (extent) {
              return {
                  x: Math.round(1/res * (lonlat.lon - extent.left)),
                  y: Math.round(1/res * (extent.top - lonlat.lat))
              };
          } 
      }
docs: Method: getOverviewPxFromLonLat
  Get a pixel location from a map location
  
  Parameters:
  lonlat - {<OpenLayers.LonLat>|Object} OpenLayers.LonLat or an
  object with a 'lon' and 'lat' properties.
  
  Returns:
  {Object} Location which is the passed-in OpenLayers.LonLat,
  translated into overview map pixels