Make a backup of this file before proceeding to edit anything. Use notepad or a text editor to edit the file hitman2.ini. At the end of the file add enableconsole 1. Now start a game and during gameplay press ~ to get the console and enter a code below

god 1 - Invincibility
giveall - All weapons
infammo - Unlimited ammo
invisible 1 - Invisibility

These cheats may only work for the beta version of the game.