I have been in the same situation as you have and I'm afraid I was not able to find a feasible way of doing this (at least not legally). I ended up needing to install my copy of Windows 7 and run the upgrade wizard provided by Microsoft.
That being said it is possible to get an installation disc for Windows 8 which commonly comes with other Windows 8 systems provided by the manufacturer however finding one of these can be tricky at best.