You don't want to use the Eloquent authentication driver.
You want to use Laravel's built in
Auth package, but don't want to use the default driver.
Switch to the database authentication driver.
app/config/auth.php and change the driver.
'driver' => 'database',
If you're using a different table than users then see Changing Your Authentication Table.
Out of the box you have two choices.
Laravel only provides an eloquent option and a database option out of the box. You can create your own driver though. See Using Your Own Authentication Driver for details.