I belive i have found a way to get beta items in the game. Simple. Just use the all-weapons cheat, best to use it in the last level, because then ALL the items. If you scroll through the inventory you may find stuff you don't normally find, two things i have found are the syringe and flashlight.
The syringe is just an item which does nothing, you can equip it, but it does nothing.
Now the flashlight is intresting. You try to equip it, the game freezes. I'm sure a PC gamer can perhaps hack the game and somehow figure this out. It would be intresting to see what these were supposed to be.