For the record, the cams themselves are not going to rust if they are made of aluminum (though they can corrode). No, instead the axles may end up rusting as these will probably be made of steel. Anything that has iron in it is prone to rust, after all.
Well, if your cams do succumb to rust, then you may be able to remove it with a wire brush. However, the best thing to do is to avoid rust altogether. What you need to do is avoid allowing the cams to store if they are not dry. So, dry them off and then lubricate them with graphite spray.