Well, firstly probably try not making a mess in the first place. Alcantara is a man made fabric, and its not as delicate as people make out. Yes care needs to be taken with it, but like anything, look after it and it will be fine. Neglect it, and it will be a mess.
Raceglaze Alcantara cleaner is a good one. And you can get fabric protectors, but with someones ass on it all day, they wear off fast!