var node = パースしたXML;

while(node){
  var child_node = node.firstChild;

  while(child_node){
    ary_0.addItem(child_node.nodeValue);
    ....
    child_node = child_node.nextSibling;
  }

  node = node.nextSibling;
}

_root.channels = [{}, {}, {}];
loadChannel('neta0.xmll', _root.channels[0]);
//laodChannel('neta1.xml',_root.channels[1]);



function loadChannel(xmlFile:String, obj:Object) {
	var x:XML = new XML();
	x.ignoreWhite = true;
	var owner = this;
	x.load(xmlFile);
	x.onLoad = function(success) {
		owner.parseChannel(this, obj);
	};
}
function parseChannel(x:XMLNode, obj:Object) {
	var channel:Array = x.firstChild.childNodes;
	// headerのパース
	obj['channelTitle'] = getValue(channel[0]);
	obj['channelLink'] = getValue(channel[1]);
	obj['channelDescription'] = getValue(channel[2]);
	obj['channelLang'] = getValue(channel[3]);
	// itemのパース
	var o = obj['items']=[];
	for (var i = 4; i<channel.length; i++) {
		var items:Array = channel[i].childNodes;
		var item:Object = {};
		item['title'] = getValue(items[0]);
		item['link'] = getValue(items[1]);
		o.push(item);
	}
	
	//ロード後のコールバックの例
	printChannel(obj);
	//
}
function getValue(xm:XMLNode) {
	return xm.firstChild.nodeValue;
}
//ロード後のコールバックの例（xmlファイルの内容を表示）
function printChannel(channel:Object){
	trace(channel.channelTitle);
	trace(channel.channelLink);
	trace(channel.channelDescription);
	trace(channel.channelLang);
	for(var i=0;i<channel.items.length;i++){
		trace(channel.items[i].title);
		trace(channel.items[i].link);
	}
}
//

var ary = ["a.xml","b.xml","c.xml"];
var len = ary.length;
var channel_count = 0;

for(var i = 0;i < len;i++){
  loadXMLFunction(ary[i]);
}

function loadXMLFunction(str){
  var tmp_xml = new XML();
  var funcOwner = this;

  tmp_xml.ignoreWhite = true;
  tmp_xml.load(str);
  tmp_xml.onLoad = function(success){
    this.parseXML_data(this);
  }
}

function parseXML_data(node){
  var tmp = new Object();

  //ここはデータにあわせてセット
  tmp["title"] = ...

  _level0["channel_"+channel_count++] = tmp;
}

<title>タイトルだよ</title>
<link>http://www.####.html
</link>
<description>Summary for """"</description>
<language>ja</language>
↓↓↓
<header title='タイトルだよ' link='http://www.####.html' description='Summary for """"' language='ja'>

これを上記のparseXML_dataで処理したら･･･

var atr_ary = ["title","link","description","language"];
var ary_len = atr_ary.length;
var obj = new Object();

for(var i = 0;i < ary_len;i++){
  obj[atr_ary[i]] = node.attributes[atr_ary[i]];
}