Via the laying on of hands, specifically with Paul. If God was to imbue men with the full power of the Holy Spirit through nothing more than His Will, then certainly Paul would be morth worthy of such an honor than anyone else throughout history. The fact that, after God had chosen Paul, the Apostles laid hands upon him to confer their gift goes a long way is supporting the passing on of the gift.
When did the Apostles do this??? Please refresh my memory --