"illuminate/database": "~5.4",
"illuminate/events": "~5.4"

<?php

use IlluminateDatabaseCapsuleManager as Capsule;

require __DIR__ . '/vendor/autoload.php';

$capsule = new Capsule;

$capsule->addConnection([
    'driver'    => 'mysql',
    'host'      => 'localhost',
    'database'  => 'database',
    'username'  => 'root',
    'password'  => 'password',
    'charset'   => 'utf8',
    'collation' => 'utf8_unicode_ci',
    'prefix'    => '',
]);

// Define o dispatcher usado pelos models do Eloquent (opcional)
use IlluminateEventsDispatcher;
use IlluminateContainerContainer;
$capsule->setEventDispatcher(new Dispatcher(new Container));

// Faz essa instancia de Capsule ficar disponível globalmente usando metodos estaticos (opcional)
$capsule->setAsGlobal();

// Configura o Eloquent ORM... (opcional e desnecessário se você já usou setEventDispatcher())
$capsule->bootEloquent();

$users = Capsule::table('users')->where('votes', '>', 100)->get();

Capsule::schema()->create('users', function($table)
{
    $table->increments('id');
    $table->string('email')->unique();
    $table->timestamps();
});

class User extends IlluminateDatabaseEloquentModel {}

$users = User::where('votes', '>', 1)->get();

...
"require": {
    "php": ">=5.6.4",
    "illuminate/database": "~5.4",
    "illuminate/events": "~5.4"
},
"autoload": {
    "psr-4": {
        "FooBarModel\": "app/Models"
    }
},
...

<?php

    namespace FooBarModel;

    use IlluminateDatabaseCapsuleManager as Capsule;
    use IlluminateEventsDispatcher;
    use IlluminateContainerContainer;

    $capsule = new Capsule;

    $capsule->addConnection([
        'driver'    => 'mysql',
        'host'      => 'localhost',
        'database'  => 'database',
        'username'  => 'root',
        'password'  => 'password',
        'charset'   => 'utf8',
        'collation' => 'utf8_unicode_ci',
        'prefix'    => '',
    ]);

    $capsule->setAsGlobal();

    $capsule->bootEloquent();

    //Cria a classe
    abstract class Model extends IlluminateDatabaseEloquentModel {}

<?php

namespace FooBarModel;

class User extends Model {}

<?php

namespace FooBarModelAdmin;

class FooBar extends FooBarModelModel {}

<?php

require __DIR__ . '/vendor/autoload.php';

<?php

require __DIR__ . '/vendor/autoload.php';

$user = new FooBarModelUserUser;

<?php

use FooBarModelUser;
use FooBarModelAdminFooBar;

require_once __DIR__ . '/../vendor/autoload.php';

$app = new SilexApplication();

$app->get('/', function ()
{
    return 'Home';
});

$app->get('/user', function ()
{
    $user = new User;
    ....
});

$app->get('/user', function ()
{
    $user = new FooBar;
    ....
});

$app->run();