Do you need to receive information, or just pass it? If the latter just use Image:
var sUrl = "servlets/myServlet?param=value";
var dummy = new Image(sUrl);
If you need to receive information you could call it in an iframe or use something like the msxml2.xmlhttp class to make a web request. Examples in these forums, search some of my old posts for "msxml2.xmlhttp".
Joe (Co-author Beginning XML, 3rd edition)