1. Scrub them with a toothbrush and regular 409 Cleaner, used liberally. Do it in small areas and wipe frequently with a clean terry cloth. (I used about 40 of them for the whole car)
2. Spray distilled water liberally after cleaning a whole seat and wipe off.
3. Let dry
4. Apply high quality leather conditioner
It did wonders for my seats. It would have cost $1000 to have them recovered. It took me about 12 hours to do the whole car. I was just amazed at how the seats turned out.