LS Server leans entirely on "Logback" for its own logging activity, so the log can be sent to any destination, provided that there is a suitable Logback appender.
As far as I know, no ready-made Logback appender for the NT event log is available.
You would have to write your own appender class, then add it to the Server classpath and configure an appender in lightstreamer_log_conf.xml based on your appender class.

We are not experts on this matter; I guess you could, alternatively, use one of the ready-made appenders to send your log to an external process which, in turn, would append the log to the NT event log. I see that a SocketAppender class is available in Logback.