The beads alone will be all the humidifying device you need, and in this case, they'll act more as a de-humidifier. I'd follow nhcigarfan's suggestion to get 65% beads and put 'em in dry. They should begin to absorb humidity and will pull the humidor's environment down to around 65% rh. If high humidity is a constant where you live, then you may have to dry the beads periodically - easily done with a blow dryer.

The beads can found here

Incidentally, 60% beads are now available.