如何获取Ajax div内容？

Question

Dim objWshShell,IE,searchStr
Set objWshShell = Wscript.CreateObject("Wscript.Shell")
Set IE = CreateObject("InternetExplorer.Application")
With IE
  .Visible = true
  .Navigate "http://site"
  Do While .Busy
    WScript.Sleep 100
  Loop
.....
.....
End With

如何获取<div id="ajax_div"></div>的内容，因为未在页面来源中显示代码。