class CString
    {
        private string value;
        private char replacement;

        public CString(params byte[] chars)
        {
            // do stuff
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Dictionary<CString, char> dict = new Dictionary<CString, char>()
            {
                { new CString(152, 147), 'A' }
            };