I think I see what he wants to do. He wants to have a web form that allows people to start a new server to their specifications. It's a very cool idea.
I think that you'd have to use php to accept the form output and create the flatfile and then use a shell command to load the server with the -f [randomly created filename].cfg. That is how I would do it as the most documentation supports the configuration file. The Teeworlds server doesn't seem to support command-line entered options except for -f (but I'm not certain).
Make sure that you put a limit on how many servers users can make, and / or require authenticated users on your site be the only ones who can make a server. A way for the creator to shut down and reconfigure their own server would be good too.
I'm an instant addict of Teeworlds. I'm currently hosting "Brad's House of Pain (bHOP)," a New England based server.