public class LogWriter:System.IO.TextWriter
{

    public override Encoding Encoding
    {
        get { return Encoding.UTF8; }
    }

    // 这里用的TextBox，当然也可以用其他组件
    private TextBox _textBox;
    public LogWriter(TextBox textBox) { _textBox = textBox; }

    public override void Write(char value)
    {
        if (_textBox.InvokeRequired)
        {
            _textBox.Invoke(new Action<char>(Write), value);
        }
        else
        {
            _textBox.AppendText(value.ToString());
        }
    }
    public override void Write(string value)
    {
        if (_textBox.InvokeRequired)
        {
            _textBox.Invoke(new Action<string>(Write), value);
        }
        else
        {
            _textBox.AppendText(value);
        }
    }

    public override void WriteLine(string value)
    {
        if (_textBox.InvokeRequired)
        {
            _textBox.Invoke(new Action<string>(WriteLine), value);
        }
        else
        {
            _textBox.AppendText(value + Environment.NewLine);
        }
    }
}

LogWriter writer = new LogWriter(this.logTextBox);
Console.SetOut(writer);