elasticsearch alias with rails

I am using rails with elasticsearch, thanks to the elasticsearch-rails gem ( http://ift.tt/2h52o5F )

I am using the repository model as described in the documentation, I can change the index, but is it possible to use the alias feature of ES? If so, how? Example:

require 'elasticsearch/persistence'
repository = Elasticsearch::Persistence::Repository.new
repository.index = "myindex" 

works fine, but no indication on how to create an alias