On his site Johannes Siipola has posted a tutorial showing how to use the Eloquent ORM outside of Laravel, more specifically the migration functionality to manage database table creation/updates/deletions.

Laravel's Eloquent is one of the most fluent and expressive ORM's available for PHP. However, unlike some of its competitors like Doctrine or Propel, it's highly tight to the Laravel ecosystem in some ways. It's still possible to use Eloquent outside Laravel with a bit of work.

[...] If you use Eloquent outside Laravel, you will be missing one of it's best features: database migrations. [...] There has been some effort in order to use Laravel migrations outside the framework, but it hasn't been possible because the migrations require a complete instance of Laravel to run. In this tutorial, we are using framework agnostic Phinx migration library instead.

He then shows how to install the packages needed for the example: Slim framework, the Eloquent ORM and Phinx. He then shows how to set up the database and Phinx configurations and create your first Phinx migration. Inside this migration he makes use of the Eloquent schema builder functionality to create a simple "widgets" table. He ends the post showing you how to create the simple Slim application and work with the model they've created to both save and read data easily.