var xmlhttp = Server.CreateObject("MSXML2.ServerXMLHTTP");
if ('light' == AuthorizeType)
{
  xmlhttp.setOption(3, 'WM id: '+reqwmid)
}
xmlhttp.open('POST', url, false);

var store = new X509Store("...", StoreLocation.LocalMachine);
store.Open(OpenFlags.ReadOnly);
X509Certificate certificate = store.Certificates[0];
request.ClientCertificates.Add(certificate);

с помощью интерфейса WebMoney Merchant;
с помощью выписки счета на оплату, используя XML-интерфейс №1;
напрямую переводить титульные знаки с доверенных кошельков клиентов, используя XML-интерфейс №2;
с помощью интерфейса Click&Buy;

Q>var xmlhttp = Server.CreateObject("MSXML2.ServerXMLHTTP");
Q>if ('light' == AuthorizeType)
Q>{
Q>  xmlhttp.setOption(3, 'WM id: '+reqwmid)
Q>}
Q>xmlhttp.open('POST', url, false);
Q>

Q>var store = new X509Store("...", StoreLocation.LocalMachine);
Q>store.Open(OpenFlags.ReadOnly);
Q>X509Certificate certificate = store.Certificates[0];
Q>request.ClientCertificates.Add(certificate);
Q>

public static string Send(Uri uri, string question, X509Certificate clientCertificate, Encoding encoding)
        {
            if (null == uri)
                throw new ArgumentNullException("uri");

            string answer;

            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
            request.ProtocolVersion = new Version(1, 0);

            if (null != clientCertificate)
                request.ClientCertificates.Add(clientCertificate);

            if (!string.IsNullOrEmpty(question))
            {
                request.Method = "POST";
                request.ContentType = "application/x-www-form-urlencoded";

                StreamWriter streamWriter = null;

                try
                {
                    Stream reqStream = request.GetRequestStream();
                    streamWriter = new StreamWriter(reqStream, encoding ?? defaultEncoding);
                    streamWriter.Write(question);
                }
                finally
                {
                    if (null != streamWriter)
                        streamWriter.Close();
                }
            }

            WebResponse response = request.GetResponse();
            StreamReader streamReader = null;

            try
            {
                streamReader = new StreamReader(response.GetResponseStream(), encoding ?? defaultEncoding);
                answer = streamReader.ReadToEnd();
            }
            finally
            {
                if (null != streamReader)
                    streamReader.Close();
            }

            return answer;
        }