Using the HtmlWeb class that comes with the Html Agility Pack, you can tweak the request before it's actually executed, like this:

    HtmlWeb web = new HtmlWeb();
    web.PreRequest = OnPreRequest;
    HtmlDocument doc = web.Load("http://wwwblablahh.com");


private static bool OnPreRequest(HttpWebRequest request)
{
    request.AllowAutoRedirect = true;
    return true;
}