How do you extract the models

[Robot J]

So I just got OG Doom 3 on Steam today and I tried the main game and it was fun. I also did a little multiplayer but back to topic. I was wondering how I could get the models from the game Specifically The BFG9000 View Model and world model. Does anyone know how to extract them and if you do could you tell me 

[Tetzlaff]

pk3 files are basically zip files. You can open them with 7zip or other zip tools.