there's no tutorial yet because the vtube studio update that allows you to have live2d pinned items released literally today lmao
you can add the example model as an item by opening it and going to the item menu (the one beside the change background button) and selecting "load current model as Live2D item". after that you can just add it and pin it to your existing model like any other item
also remember to have the plugin connected for the model to appear