Testing database application is hard enough when you have only one server. When you need to test performance and scalability by involving multiple servers, then you need either a lot of patience or a tool that can simplify your task.
Using MySQL Sandbox, you can install single or multiple nodes in one host. Combining that with Gearman, a client/server infrastructure for generic tasks, you can work on distributed servers easily, with little worry about the details.
No matter what language you speak, Gearman can meet your needs in C, PHP, Perl, Ruby, shell scripting, and several more.