Ah, that helped. I was able to get it started on that machine and get data logging. I'm currently digging through some other issues so knowing how to start logging like that is exactly what I needed. Somehow I'd missed it in the documentation. 
Just to add, for reference to others - the debug documentation is available at => https://www.elastic.co/guide/en/beats/libbeat/current/command-line-options.html. I also ended up with a subsequent question, that maybe should have been attached to this thread but I've started a new topic located here and linked for future reference.