Wikipedia has a table of similar symbols.
In C#, to make a char literal corresponding to U+2022 (for example) use '\u2022'. (It's also fine to cast an integer literal as you do in your question, (char)8226)
Late addition. The reason why your original approach was unsuccessful, is that the value 149 you had is not a Unicode code point. Instead it comes from Windows-1252, and Windows-1252 is not a subset of Unicode. In Unicode, decimal 149 means the C1 control code "Message Waiting".
You could translate from Windows-1252 with:
textBoxNewPassword.PasswordChar = 
  Encoding.GetEncoding("Windows-1252").GetString(new byte[] { 149, })[0];
but it is easier to use the Unicode value directly of course.
In newer versions of .NET, you need to call:
Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
before you can use something like Encoding.GetEncoding("Windows-1252").