Stakeholders should handle the business, not the developers. That should be the focus when dealing with cowboys: wresting control back to the customer and help them slow down their frantic code herding. Pull in the reins if you will.
A quick recap: Cowboys have seized control over the process. This means a lot of time is spent doing stuff they think is most important and not necessarily what is most valuable for their customers. And here lies the key to success: get the organization back to being in a constant focus on providing customer value.
The first step is talking to them about value-driven development, minimum marketable features and the importance of that throughout the entire development process. Explain why "business value" is the language they should be using when defining work items and not technical features. This is the easiest and most hands-on way to begin the transformation. It's also the only way customers and stakeholders can understand what the programmers are actually working on.
