Find the "hitmancontracts.ini" file in your C:Program FilesEidosHitman Contracts directory. Add the following two lines to the end of it and save changes:

ENABLECONSOLE 1
EnableCheats 1

Now when you press Shift+Esc ingame, you can access a cheats menu which will allow you a range of things like God Mode, infinite ammunition, control over the speed of time, the ability to teleport and more!