How to VBA sends a Async XMLHTTP request?
===

I need to get data from webservice in Excel, then I have created a excel addin provide function to get it; user just need type in cell:
`=sendRequest("http://webservice.com")`
I have 2 excel file to demo about send request, I wrote in 2 way, you can download here: 1.[synchronous][1] and 2.[asynchronous][2]

In sync way, the function can send request and get data nomarly. But, we have 100, 200 cell call it, we lose so much time to wait loading. My solution is using Async way. In this way, the function exist immediately after `.send`

    Public Function sendAsyncRequest(URL)
        ..... 'another satement
        ' Get some stuff asynchronously.
        xmlHttpRequest.Open "GET", URL, True
        xmlHttpRequest.send
    End Function
And return value in cell, that call request function, alway is zero 0 instead of repsone text.
I'm must use my handler class to bindding it with `OnReadyStateChange` of `xmlHttpRequest object` to set response text into cell. Then it clear cells formula. 

So my question is How to change the display text of cell without changing its formula?
Has these another solution to send request and get return value?

  [1]: https://dl.dropbox.com/u/60740207/TestHttpReqest%20-%20Sync.xlsm
  [2]: https://dl.dropbox.com/u/60740207/TestHttpReqest%20-%20ASync.xlsm