Thanks for posting this, it really helped me get going. I used it to get it to get kopf running on Elasticsearch 2.3.3 under OS X 10.11 with homebrew 0.9.9 and found there are a few minor changes:
By default, the `plugin` executable wasn’t in my path. I was able to find it at `/usr/local/Cellar/elasticsearch/2.3.3/libexec/bin/plugin`.
The syntax for `plugin` has changed a little. The two hyphens are no longer needed, the is now: `plugin install lmenezes/elasticsearch-kopf`.
Homebrew now has a systemd-like system for starting/stopping services, so you can restart Elasticsearch with: `brew services restart elasticsearch`