I had a few stains and I used laundry detergent as suggest from others on the web. dilute it with a lot of water and soak the carpet. wait a few minutes and then wet vac it out. I did this with my wife on a relativly hot day and it was dry within the afternoon. Some stains came out, some are better looking and some are still there, but the smell is much better even at 3 weeks later.
Replaced the carpet in my 80 Trans Am back in highschool. Seatbelts, console, some trim components, and seats must come off, other than that it was easy, just took a little time to get it right.