I just updated the "InstallerApp2ISO.sh" to include 10.8.x installers. It should work in theory. Could you give it a try and let me know, either here or in the "[HowTo] Create OSX ISO from the OSX Install app" thread, where you can get the script from?
Actually, can you do me a favor and run the following command? Just copy/paste the whole thing in the Terminal. This is assuming that the "InstallerApp2ISO.sh" is located in "/Users/user/Downloads" (the default):
/Users/user/Downloads/InstallerApp2ISO.sh -i "/Applications/Install OS X Mountain Lion.app" -v 2