You can toggle on Scriptwriting mode by going to Format → Scriptwriting or Ctrl+8, so it’s easy enough to go back and forth between scriptwriting and regular composition within the same project.
If you’re not familiar with Scriptwriting mode, §19.1 of the Scrivener manual (which you can find under the Help menu) is a good primer.
Excellent answer. Two minutes later I have created an example and know how to use Ctrl-\ to invoke the element menu. And there are unexpected goodies like tab does parentheticals inside e.g. dialogue.