You don't actually get to sit in the cockpit. The winner will get his or her image displayed on the one-to-one scale's virtual cockpit. Thus, the lucky winner will need to provide pictures so the Gundam wizards can insert him or her onto the cockpit screen.
Did I say "lucky"? I meant wealthy! The auction is currently at close to ¥800,000, which is nearly US$10,000. The money does go to a good cause: rebuilding those areas hit hardest by the Tohoku Earthquake.