Como devo construir a entidade para atingir essa solicitação de postagem?

POST https://picasaweb.google.com/data/feed/api/user/userID/albumid/albumID/photoid/photoID

<entry xmlns='http://www.w3.org/2005/Atom'>
  <content>great photo!</content>
  <category scheme="http://schemas.google.com/g/2005#kind"
    term="http://schemas.google.com/photos/2007#comment"/>
</entry>

É de:http://code.google.com/intl/zh-TW/apis/picasaweb/docs/2.0/developers_guide_protocol.html#AddComments

Alguém poderia dar um exemplo ou alguma dica? Muito Obrigado.

UPDATE: Adicionei meu código aqui:

        List<Header> headers = new ArrayList<Header>();
    headers.add(new BasicHeader("GData-Version", "2"));
    headers.add(new BasicHeader("Authorization", "GoogleLogin auth=" + mAuthToken));

    EntityTemplate entity = new EntityTemplate(new ContentProducer() {
        public void writeTo(OutputStream ostream) throws IOException {
            Writer writer = new OutputStreamWriter(ostream, "UTF-8");

            writer.write("\r\n");
            writer.write("<entry xmlns='http://www.w3.org/2005/Atom'>");
            writer.write("<content>" + comment + "</content>");
            writer.write("<category scheme=\"http://schemas.google.com/g/2005#kind\"\r\n");
            writer.write("term=\"http://schemas.google.com/photos/2007#comment\"/>");
            writer.write("</entry>\r\n");

            writer.flush();
        }
    });

Ainda sem sorte. Qualquer ideia?