I'm a little bit of a newbie to Laravel. However, I'm working through L5 a little at the moment.

I've been trying to adjust the router for a different purpose, but in a similar way. (I want to alter the $router->model() method to allow for slugs as well as ids).

Reviewing the code, the HTTP Kernel is passed the $router instance very early on, and it's no longer tied to the container's version. (line 49 of public/index.php).

$kernel = $app->make('Illuminate\Contracts\Http\Kernel');

Then in 'handle', the kernel processes everything before passing to the router, (line 80, Illuminate/Foundation/Http/Kernel)

public function handle($request)
{
	try
	{
		$response = $this->sendRequestThroughRouter($request);
	}
	catch (Exception $e)
	{
		$this->reportException($e);

		$response = $this->renderException($request, $e);
	}

	$this->app['events']->fire('kernel.handled', [$request, $response]);

	return $response;
}

A part of this is the dispatchToRouter method (line 208)

protected function dispatchToRouter()
{
	return function($request)
	{
		$this->app->instance('request', $request);

		return $this->router->dispatch($request);
	};
}

As you can see, it's using the kernel's stored router - rather than the one we've set through the ServiceProvider.

As a temp fix to test, I've altered the method to:

protected function dispatchToRouter()
{
    $this->router = $this->app['router'];
    
    return function($request)
    {
        $this->app->instance('request', $request);

        return $this->router->dispatch($request);
    };
}

I'm sure there is a better way, but this may give some clues? It doesn't fix everything - for example Middlewares get run on the original router, not the one we use at the end in this test change.