I was told you are not supposed to put anything on your lambskin. If you want it cleaned it needs to be sent to Chanel. Do not put any preliminary sprays or polishes on it.
I've watched Chanel boutique SA's put products from leather conditioners and cleaners to waterproof sprays on bags at the store. If they do it, it's fine for me to do it, but each person should decide this for themselves.