Adam Machanic has made the SQLQueryStress source code publicly available:
So here’s the official word: The attached source code is hereby released to the world, copyright and royalty free. You may use it, if you like, for whatever you want. Enjoy! If you use it for a public project, I would appreciate a mention in the acknowledgements section, but even that is not required. This source code is yours, warts and all. I was tempted to do some cleanup work, but at this point it’s just not something I’m ever going to touch again. I upgraded the project from Visual Studio 2005 to Visual Studio 2013, confirmed that it builds and seems to work, and that’s that.
Adam may never have used in a production scenario, but I certainly have, and SQLQueryStress is still the best free load simulator. There’s also a GitHub repo thanks to Erik Ejlskov Jensen, so go forth and hack at some C# code.