Creating multiboot Windows 8/8.1 without typing Installation Keys, need help!

Hey, MDL. I'm new to the forum, so I apologize if I mess up.

I've recently made a Windows 8 and a Windows 8.1 installation disc from the ISO images on MSDN. Each image includes Core/Core VL and Pro/Pro VL, 32 and 64 bit editions of each. I have the installation keys for all of these installations, but I don't want to have to type an installation key every time I go to use this disc. I've tried adding an installation key using WinReducer8 (which I do not recommend), but it only adds one key, which means I cannot choose which edition I want to install.

When I made my AIO Windows 7 ISO, I had no issues, as Windows 7 doesn't force you to add an installation or product key; you select your desired edition and you're good to go. Attached Image 1 shows what I'm referring to.

Now, however, Windows 8 has to choose your edition by the product key you enter (well played, Microsoft), and I want to find a way around this. Any ideas? If at all possible, I'd like to avoid programs to do this, but am open to suggestions. Thanks in advance!

 

Did this, and now the ISO is not bootable in VirtualBox or VMWare. I copied and pasted what you typed right into a text document, saved as EI.CFG on desktop, moved to where I have the files extracted to my hard drive, "F:\Disk Images\Win8.1AIO\Disk Files\sources\ei.cfg" Open all the documents in MagicISO, make sure it says "Bootable," and attempt to use in VBox and VMware, says BCD is corrupt. Thoughts?

 

Thanks for the suggestion, Tito. I downloaded the trial of UltraISO, and I followed the same steps:
1. Extract Boot Image File (.bif) from original ISO using UltraISO
2. Extract ISO to location on hard drive
3. Edit ei.cfg to include text mentioned by abbodi1406 (thanks again)
4. Rebuild ISO using UltraISO, including Win8.1.bif

However, testing this new image in VirtualBox and VMware still results in "BOOTMGR is corrupt" and "The file is possibly corrupt. Please check the file header checksum." The ISO I had originally made still works fine. Thanks again for the help.

 

I'm testing this now, I didn't see this before I replied to @tito. Thanks again.

EDIT: Thanks to abbodi1406, I got this image to work. I thought I had to repack the ISO image every time, I didn't think to just edit it using UltraISO. Oops

 

I know that now. I had only known to extract the iso in order to be able to edit it. It's amazing how oblivious to how many ways there are to do just one task.

 

Good tip, I'll keep that in mind later. For now, I managed to make it bootable with UltraISO. Works great, thanks for the help, everyone!