Not really an Ajax topic but you have two basic approaches:
1) Automate Internet explorer to duplicate your manual actions. Can be difficult to allow for errors etc.
2) Use a programmatic way to access the pages using something like XmlHttp. For example use the msxml2.xmlhttp.4.0 class to send a GET/POST request with the necessary request data.
Try seacrhing Google groups in Microsoft.public.* for internetexplorer.application and XmlHttp.
Joe (Microsoft MVP - XML