Setting an alternate controller folder location in ASP.NET MVC

We can an MVC app that uses the default folder conventions for the HTML views, but we'd like to set up alternate "Services" folder with controllers used only for web services returning xml or json.

So the route "/Services/Tasks/List" would be routed to "/Services/TaskService.cs", while "/Tasks/List" would be routed to the standard "/Controllers/TaskController.cs"

We'd like to keep the service controllers separate from the view controllers. We don't think areas or using another project will work. What would be the best way to approach this?