WebRequest怎么设置socks5代理

WebRequest如何设置socks5代理？
翻遍百度和谷歌就是找不到，只好来请教各位大虾了。

C# code

            WebRequest request = WebRequest.Create ("http://www.contoso.com/default.html");            request.Credentials = CredentialCache.DefaultCredentials;            request.Proxy = xxx?            HttpWebResponse response = (HttpWebResponse)request.GetResponse ();            Console.WriteLine (response.StatusDescription);            Stream dataStream = response.GetResponseStream ();            StreamReader reader = new StreamReader (dataStream);            string responseFromServer = reader.ReadToEnd ();            Console.WriteLine (responseFromServer);            reader.Close ();            dataStream.Close ();            response.Close ();

XML code

<system.net>      <connectionManagement>      </connectionManagement>     <defaultProxy>        <proxy proxyaddress="http://xxx.xxx.xxx.xxx:xxx" bypassonlocal="False"/>      </defaultProxy>     <settings>          <httpWebRequest useUnsafeHeaderParsing="true"/>         <servicePointManager checkCertificateName="true"                                checkCertificateRevocationList="true"                                 enableDnsRoundRobin="true"                                expect100Continue="true"                                  useNagleAlgorithm="true"/>        </settings>   </system.net>
[解决办法]
socket 5? 没注意看。。。我记得 WebProxy 是不支持编程方式设置socket代理的。

参考：http://social.msdn.microsoft.com/Forums/en-US/ncl/thread/982bef6c-b9a4-4c0d-b7d5-0c64df9f610a