* It is easier to just install a Linux 3.15 kernel. I installed the latest RC on Ubuntu 14.04 and that did the trick.
* You should not have to install Mountain Lion first. I made a Mavericks ISO using the script mentioned and it installed without any issues
* The Qemu that ships with Ubuntu 14.04 is new enough. No need to compile your own. Those patches are pretty old and if your distro is up to date then you most likely already have a Qemu that just works.
This posting also has more info http://blog.ostanin.org/2014/02/11/playing-with-mac-os-x-on-...
Edit: try this out another time - you need access to an OSX machine to do various steps of the process.