To be completely honest my thoughts were - This is impossible without cheats. My trick was really to just use this site
Put them in, then use the save exploit at the end of the game
(Save the game at the end, start a new game on any level, then reload your save) Game doesnt know you've cheated and you've easily completed it.
I'm sorry but the least steps some were insanely impossible without the cheats. Being able to fire the energy balls and place portals Anywhere was just like a gift from god.