By that, I assume you mean install Windows 8 from an external USB DVD-drive. I think it would work, but you'll have to try it to find out.
If it doesn't work, you may need to change a BIOS setting. My BIOS has an option for enabled USB ports at boot. You may have something similar. If you do, set it to "full" or something like that. If you don't have that option, unplug your mouse and plug the DVD-drive into the port (assuming it is a USB DVD-drive).
Hope this helps!