How to access controller located as part of another application in plugins directory

Hey all,

I installed blogkit as a rails plugin. It installed in the vendor
directory as an entire application. called blog_kit. This application
has a controller called blog_posts_controller. However, when I route to
blog_posts in my application:

   resources :blog_posts do
       resources :blog_comments
       resources :blog_images

       collection do
           get :drafts

       member do
           get :tag

It gives uninitialized constant BlogPostsController, because it doesn't
know where to find the controller.

Any idea how to get it to recognize the controller in vendor folder?

Thanks for response.