How do I use ElasticSearch on Hatchbox?

Simply tag one of your servers with the elasticsearch tag and ElasticSearch will be installed for you to use.
Your server must have at least 4GB of free RAM for ElasticSearch to run. Any less and it will probably fail to start. You can run this on the same server with your Rails app if you like, but you will probably need an 8GB server to run everything.