loder.onLoad   = LoadCallBack;
loder.in_num   = 1;//ここで設定
loder.load("URL");
 
// コールバック
function LoadCallBack(success:Boolean):Void{
	if(success){
		_global.test[this.in_num] = this.inputtext;
	}
}

var loder:LoadVars = new LoadVars();
loder.onwer:Object = this;
loder.onLoad = function(success:Boolean){
    var in_num:Number = doSomething();
    this.owner.loadCallBack(success,in_num,this);
}
loder.load("URL");

//コールバック
function loadCallBack(success:Boolean, in_num:Number,aLoader:LoadVars):Void{
  if(success){
    test[in_num] = aLoader.inputtext;
  }
}

var loder:LoadVars = new LoadVars();
loder.onLoad = LoadCallBack(0);
loder.load("URL");
//コールバック
function LoadCallBack(in_num:Number):Function {
    return function (success:Boolean):Void {
        if (success) {
            test[in_num] = this.inputtext;
        }
    };
}