If there's no way to inherit from or inject into a Fae class, your last effort would be to override it. To do that, simply copy the Fae class into your application in the same path found in Fae and customize it from there.
E.g. if you need to customize Fae's image_controller.rb, copy the file from Fae into your application at app/controllers/fae/image_controller.rb.
If you need to override the uploaders Fae::Image and Fae::File use, you can use the method in the previous section. To customize the Fae::ImageUploader just copy file to app/uploaders/fae/image_uploader.rb and make your updates.
This is handy when you need to update the extension_white_list or set your own resizing logic.
Note: If you just need to increase the file upload limit, see the options in Initializer, no need to override the whole file.
In config/initializers/fae.rb:
config.max_image_upload_size = x
config.max_file_upload_size = x