Turpentine and a rag or green kitchen scrubber? Obviously the metal/painted bits will be more resilient and probably not suffer.

How to Remove Latex Paint Stains | HowStuffWorks

I got bored before I found anything definitive.

Speaking personally I would try Turpentine and a rag or green kitchen scrubber on the saddle as well and if it damaged stuff then I would buy a new saddle.