Try removing all unnecessary decoration and repeat xcoding. Authors are not responsible of results of use or inability to use XCode program. You are using the program at your own risk. XCode Source Code Yep. Download XCode sources now and do with them whatever you want.
Commercial use is perfectly ok, as well as omitting credits to the authors.
You don't need to ask for a permission, just do what you find appropriate. Here's an archive of the events. The results of actual programming are probably less interesting than message threads that accompanied the process.