Hexen II Mission Pack: Portal of Praevus Hints & Cheats

To play as the Demoness class in the original Hexen II scenario, first start a a new game with any class/difficulty, then enter the console using the ~ key.
Enter "_cl_playerclass 5" into the console followed by "map demo1". You will begin the original scenario playing as the Demoness. You can also adjust the difficulty setting by entering "skill 0-3" before entering the map command. The higher number means higher difficulty.