Bundler: how to use without rails?

Digging through the Bundler website:

1. Create Gemfile (run bundle init to create skeleton Gemfile)
2. bundle install

3. In your app:

   # Only needed for ruby 1.8.x
   require 'rubygems'
   
   # The part that activates bundler in your app
   require 'bundler/setup' 
   
   # require your gems as usual
   require 'some_gem'
   
   # ...or require all the gems in one statement
   Bundler.require
   

Could be worth checking out:

Bundler.io - Using Bundler in Your Appplication
Bundler.io - Bundler.setup and Bundler.require

Are bundle exec and require 'bundler/setup' equivalent?