from what i understand, what you are trying to do isnt supported by any OLE/ODBC provider I know of. Usually you encrypt a password when saved in a file (like web.config or whatever), read it in your application, decrypt it, build connection string, connect to server.
If you are concerned about plain text, etc, you need to encrypt your connection, or use integrated authentication instead (as integrated stores no password, its windows auth)
secure connection: