It can be possible but will require more code and work to do it as you will have to write basic XML HTTP calls to accomplish
I don't have ready sample for it but you can start with these
http://aspsnippets.com/Articles/AJAX-Calls-Using-JavaScript-And-XMLHTTP-in-ASP.Net.aspx
http://aspsnippets.com/Articles/Custom-Ajax-Enabled-Grid-using-JavaScript-xmlhttp-in-ASP.Net.aspx
But I suggest using jQuery as it is Cross browser solution