Do you have a source in mind able to manufacture HuCards?
There's scores of options, just a matter of selecting one.
Got any good leads, or just asking out of curiosity?
Necromancer: good point. I don't think it'd be hard to query the hardware for existing memory, and then use whatever's required.
guyjin: Not sure yet. It would be easiest to use a menu, especially if three BIOSes are supported (CDROM system 1, CDROM system 3, Games Express).