I’ve just created a Windows 8 VM to test it out, I unzipped it from the ISO on another machine and then stupidly deleted it, leaving the folder. Here’s how you can recreate the ISO from the folder.
hdiutil makehybrid -o ~/Downloads/Win8.iso ~/Downloads/SW_DVD5_Win_Pro_8_64BIT_English_MLF_X18-16134/ -iso -joliet
