Custom JsonWriter

public class XmlJsonWriter : JsonWriter
{
    private readonly XmlWriter _writer;
    private string _propertyName;

    public XmlJsonWriter(XmlWriter writer)
    {
        _writer = writer;
    }

    public override void WriteComment(string text)
    {
        base.WriteComment(text);
        _writer.WriteComment(text);
    }

    public override void WritePropertyName(string name)
    {
        base.WritePropertyName(name);
        _propertyName = name;
    }

    public override void WriteNull()
    {
        base.WriteNull();

        WriteValueElement(JTokenType.Null);
        _writer.WriteEndElement();
    }

    public override void WriteValue(DateTime value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.Date);
        _writer.WriteValue(value);
        _writer.WriteEndElement();
    }

    public override void WriteValue(DateTimeOffset value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.Date);
        _writer.WriteValue(value);
        _writer.WriteEndElement();
    }

    public override void WriteValue(Guid value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.Guid);
        _writer.WriteValue(value.ToString());
        _writer.WriteEndElement();
    }

    public override void WriteValue(TimeSpan value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.TimeSpan);
        _writer.WriteValue(value);
        _writer.WriteEndElement();
    }

    public override void WriteValue(Uri value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.Uri);
        _writer.WriteValue(value);
        _writer.WriteEndElement();
    }

    public override void WriteValue(string value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.String);
        _writer.WriteValue(value);
        _writer.WriteEndElement();
    }

    public override void WriteValue(int value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.Integer);
        _writer.WriteValue(value);
        _writer.WriteEndElement();
    }

    public override void WriteValue(long value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.Integer);
        _writer.WriteValue(value);
        _writer.WriteEndElement();
    }

    public override void WriteValue(short value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.Integer);
        _writer.WriteValue(value);
        _writer.WriteEndElement();
    }

    public override void WriteValue(byte value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.Integer);
        _writer.WriteValue(value);
        _writer.WriteEndElement();
    }

    public override void WriteValue(bool value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.Boolean);
        _writer.WriteValue(value);
        _writer.WriteEndElement();
    }

    public override void WriteValue(char value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.String);
        _writer.WriteValue(value.ToString(CultureInfo.InvariantCulture));
        _writer.WriteEndElement();
    }

    public override void WriteValue(decimal value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.Float);
        _writer.WriteValue(value);
        _writer.WriteEndElement();
    }

    public override void WriteValue(double value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.Float);
        _writer.WriteValue(value);
        _writer.WriteEndElement();
    }

    public override void WriteValue(float value)
    {
        base.WriteValue(value);

        WriteValueElement(JTokenType.Float);
        _writer.WriteValue(value);
        _writer.WriteEndElement();
    }

    private void WriteValueElement(JTokenType type)
    {
        if (_propertyName != null)
        {
            WriteValueElement(_propertyName, type);
            _propertyName = null;
        }
        else
        {
            WriteValueElement("Item", type);
        }
    }

    private void WriteValueElement(string elementName, JTokenType type)
    {
        _writer.WriteStartElement(elementName);
        _writer.WriteAttributeString("type", type.ToString());
    }

    public override void WriteStartArray()
    {
        bool isStart = (WriteState == WriteState.Start);

        base.WriteStartArray();

        if (isStart)
        {
            WriteValueElement("Root", JTokenType.Array);
        }
        else
        {
            WriteValueElement(JTokenType.Array);
        }
    }

    public override void WriteStartObject()
    {
        bool isStart = (WriteState == WriteState.Start);

        base.WriteStartObject();

        if (isStart)
        {
            WriteValueElement("Root", JTokenType.Object);
        }
        else
        {
            WriteValueElement(JTokenType.Object);
        }
    }

    public override void WriteStartConstructor(string name)
    {
        bool isStart = (WriteState == WriteState.Start);

        base.WriteStartConstructor(name);

        if (isStart)
        {
            WriteValueElement("Root", JTokenType.Constructor);
        }
        else
        {
            WriteValueElement(JTokenType.Constructor);
        }

        _writer.WriteAttributeString("name", name);
    }

    public override void WriteEndArray()
    {
        base.WriteEndArray();
        _writer.WriteEndElement();
    }

    public override void WriteEndObject()
    {
        base.WriteEndObject();
        _writer.WriteEndElement();
    }

    public override void WriteEndConstructor()
    {
        base.WriteEndConstructor();
        _writer.WriteEndElement();
    }

    public override void Flush()
    {
        _writer.Flush();
    }

    protected override void WriteIndent()
    {
        _writer.WriteWhitespace(Environment.NewLine);

        // levels of indentation multiplied by the indent count
        int currentIndentCount = Top * 2;

        while (currentIndentCount > 0)
        {
            // write up to a max of 10 characters at once to avoid creating too many new strings
            int writeCount = Math.Min(currentIndentCount, 10);

            _writer.WriteWhitespace(new string(' ', writeCount));

            currentIndentCount -= writeCount;
        }
    }
}

var user = new
{
    Name = "James",
    Age = 30,
    Enabled = true,
    Roles = new[]
    {
        "Publisher",
        "Administrator"
    }
};

StringWriter sw = new StringWriter();

using (XmlWriter xmlWriter = XmlWriter.Create(sw, new XmlWriterSettings { OmitXmlDeclaration = true }))
using (XmlJsonWriter writer = new XmlJsonWriter(xmlWriter))
{
    writer.Formatting = Formatting.Indented;

    JsonSerializer serializer = new JsonSerializer();
    serializer.Serialize(writer, user);
}

Console.WriteLine(sw.ToString());
//<Root type="Object">
//  <Name type="String">James</Name>
//  <Age type="Integer">30</Age>
//  <Enabled type="Boolean">true</Enabled>
//  <Roles type="Array">
//    <Item type="String">Publisher</Item>
//    <Item type="String">Administrator</Item>
//  </Roles>
//</Root>