The only ways to get it to run without DirectX nine is either use the application runtime (which isn't really an option for games, as it has no graphics engine) or code a new runtime that uses something different like OpenGL, DirectX 8 or a software renderer.
Same answer as before. If you want the runtime to use anything other than the current version of DirectX nine, you'll have to code it yourself. I can't help you any more than that, otherwise I would've tried to have written a direct X 8 runtime myself!
The usual solution is to link to or bundle the DirectX August 2008 update with your game so people can update if they're not already up to date. What's different about your situation? Perhaps there's another solution, depending on exactly what you want to do.