[Koha] Changing Member Card Number?

Hi all: I'm testing koha version 1.2.3 for our library at the ISPJAE university in Cuba. I'm interested to know how I can change the default card number's value that koha assigns to a new member by the card number that the members already have. I need this because all students, professors and workers here have their own card number valid for all the campus. Best regards... Ing. Ramsés Guilbeaux Cantillo Instituto Superior Politécnico "José Antonio Echeverría" Ciudad de la Habana, CUBA