The “Script Settings…” choice in that menu is how you set up your own scripts. The settings in here are documented in §19.6, Creating Your Own Script Formats, in the user manual PDF.
Alas though, I don’t think you’ll be able to actually pull this look off with the black bar bit. Scrivener has no way of drawing elements across the entire sheet of paper like that, and its text highlighter tool is more of a highlighter and less of a box-like background element—it tends to stick to where visible text is.
Probably best to stick with a rough cut draft in Scrivener, and exporting with the element assignments set up the way you want, and prepared for proper format adjustment in a more dedicated page layout program.
Ah, that’s a pity, but thanks for the information - I will have a look at that section of the manual. If it isn’t possible to achieve anything close, then it’s probably a case of doing as you suggested, and formatting elsewhere. Cheers