Add this line to your application's Gemfile:

gem 'omniauth-liblynx'

Adding the middleware to a Rails app in config/initializers/omniauth.rb:

Rails.application.config.middleware.use OmniAuth::Builder do
  provider :liblynx, ENV['LIBLYNX_ID'], ENV['LIBLYNX_SECRET']
end

Read the OmniAuth docs for detailed instructions: https://github.com/intridea/omniauth.