One option: set the default and highlight colors as properties of the polygon.
for (var t=0; t< lAll_Areas.length; t++) {
var n = //arbitrary number 0<n<255;
var m = (255-cd).toString();
var col = 'rgb(' + n + ',' + m + ',0)';
lAll_Areas[t].defaultColor = col;
lAll_Areas[t].highlightColor = 'rgb(0,255,255)';
lAll_Areas[t].setOptions({ fillColor: col });
}
Then:
google.maps.event.addListener(MapArea, "mouseover", function () {
this.setOptions({ fillColor: this.highlightColor });
});
google.maps.event.addListener(MapArea, "mouseout", function () {
this.setOptions({ fillColor: this.defaultColor });
});