There are three different versions of Hackboot we'll need to use two of them in this guide. To help Mountain Lion start, you'll need to use Olarila's Hackboot CD. Hackboot 1 / Hackboot 2: Even though it's called a 'bootable DVD', the Olarila version of OS X Mountain Lion still can't boot in Virtualbox by itself.In the past, we've used the iAtkos distro for this, but iAtkos hasn't updated for Mountain Lion yet, so I used the 'OS X 10.8 Mountain Lion bootable DVD for Intel PCs', by Olarila. I won't go into details, but you can download these copies from about any bittorrent website by using a bittorrent client (it's about 4.5 GB in size).
Instead, you'll have to rely on pirated 'bootable DVD' copies of Mountain Lion, also known as 'distros'.