Do you want new scenario for this game? Do you want make a new one?
From this link, you can download a layered PhotoShop PSD File with all the elements needed to compile a custom scenario.
The file include also the elements from the "Stallion" and "Red Rock Tomahawk" expansions.
https://goo.gl/oNAjJz
Let me know if you have problem to use it.
And, above all, share with me the scenario you'll create.