Using Windows 8 .img file to create a bootable USB thumb drive Is it possible to create a bootable USB drive for installing Windows 8 without access to a copy of Windows? 

I know I could install a VM and install Windows there, then make the bootable drive and use Bootcamp to actually install that way, but honestly I would rather not have to put the extra software on my system if at all possible.

I checked the Bootcamp documentation and it says I may have the option to "create a windows installation disk" but I don't have that option (unsure why?)

Additional information:
USB Key capacity: 1 16gb and 1 30gb
OS ver: OSX Mountain Lion
Machine: Late 2010 MacBook Air
It seems Bootcamp Assistant should be able to help you with this (especially as you have a MacBook Air). It odd that it doesn't. Another weird move from Apple. Because of this you may need to do some system editing, as ethanlee16 points out, to convince BA to give you the option of creating a Bootable USB. 

Follow his instructions, or if you don't want to go into terminal, follow these instructions. 

And then follow these:

First, convert your Windows 8 .img file to an .iso file. You can do this within OSX by following these simple instructions.

Next, just use the new .iso image with Bootcamp Assistant to create a bootable USB drive with Windows 8 on it. These instructions (as posted by Alexandr Mazanov in the comments) do a great job of explaining what to do.

No need for Windows or any VMWare. Good luck!