How to update data in a Repeater row-by-row using old-fashion asynch CallBacks

In my application I hook into the ICallbackEventHandler to make pre-asp.net 3.0 aynch callbacks. This callback is limited to a very simple area of an order input screen, which I used mostly to experiement with callbacks; and as a result, the code ended up working so I kept it.
Now, I'd like to experiment with Ajaxifying my Repeater object. I currently use the UpdatePanel, but I am not satisified because it freezes the links and controls that exist within the UpdatePanel. I understand it works that way because everything inside the UpdatePanel is getting refreshsed.
As a result, I would like to experiment with using that old-fasion CallBack code to update each row in my Repeater object one-by-one. However, I need some ideas on how the asynch callback can be called by each row in my repeater.
For example, here's a simple javascript function called ProcessText (called by another js function that was triggered by a OnBlur() on some text fields.

function processText()
{    
    var objCur1Amt     = document.getElementById(txtQuoteCur1AmtID);
    var objCur2Amt     = document.getElementById(txtQuoteCur2AmtID);
    callserver(objCur1Amt.value + ";" + objCur2Amt.value);
}

// come back from the server side event
function ReceiveServerData(arg, context)
{
    FormatBuySell(arg);
}

function FormatBuySell(arg){
    argArray = arg.split(";");  
    var objCur1Amt     = document.getElementById(txtQuoteCur1AmtID);
    var objCur2Amt     = document.getElementById(txtQuoteCur2AmtID);
    objCur1Amt.value = argArray[0].toString();
    objCur2Amt.value = argArray[1].toString();
}

Here's part of the repeater on my aspx page:

<asp:Repeater ID="Repeater1" ... >
<ItemTemplate>
    <tr align="center" id="trTagOrder"  runat="server" >  
     <td id="tdBuySell">
        <asp:Label ID="lblBuySell" Text='<% #Eval("buy_sell") %>' runat="server" ></asp:Label>
     </td>
    .
    .
    </tr>
    </ItemTemplate>    
    </asp:Repeater>

On the server side Repeater1_ItemDataBound event I can get a handle on each <tr> object as follows :

   HtmlTableRow tr = (HtmlTableRow)e.Item.FindControl("trTagOrder");

then I can use something like tr.BgColor = myColor in order to update the row's background color, for example.

This all works great but I'd like to figure out how to do this row-by-row WITHOUT leaving it up to the UpdatePanel to do the work for me.

Any ideas ?
Thank you sincerely,
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