■flaの方
var dat = new Array();

for(i = 0;i < 50;i++){
	dat.addItem({aaa:i+"行目",bbb:i % 3});
}
grid.dataProvider = dat;
grid.getColumnAt(1).cellRenderer = "ExtraComboRenderer";

■asの方
function setValue(str:String, item:Object, sel:Boolean) : Void
{
Combo._visible = (item!=undefined);
Combo.dataProvider = cards2;
Combo.editable=true;
//Combo.getItemAt(1).label;

Combo.selectedIndex = str;
}