MacOS – Fresh Install of Mountain Lion on MacBook Pro Retina that upgraded via a voucher

Since you've never purchased it from the App Store, you cannot re-download iPhoto from the App Store (unless you buy it again).

The only way you get re-download rights to iLife on the App Store is if you either purchased it from the App Store or bought a Mac that does not come with a software re-install disc.

You should be able to use dd to destroy the partition's header. You can then format (erase) it and run the install.

From the installer run Terminal and type the following:

dd if=/dev/zero of=/dev/disk0s2 bs=1024 count=1024

Do be warned, this will irrecoverably destroy all data on that partition. But it looks like that's what you're expecting. Make sure you don't accidentally target the wrong thing.

Also note that I haven't done this, exactly. I've used this technique to destroy the entire partition table, not just a single partition. But I think it should work.

When you're done quit Terminal and run Disk Utility. You won't get any complaints about Core Storage.