Cross-X's original answer to this question is correct.
However, the concern that such a device could be employed as, or construed as, an evasion of the regulation on transfers is not invalid. Therefore, I recommend to people (as LenS suggested) that the recipient of the weapon give the donor/owner of the weapon a receipt acknowledging that he is taking possession of the weapon for safe storage purposes only and without acquiring any right, title or interest in the weapon for himself.
However, there is a problem with such an arrangement, and that has to do with undoing it at the other end. If you have consenual possession of the property of another, you are obliged to give it back to him on demand. However, you cannot give physical possession of a weapon to an unlicensed person. So if Fred comes to you a few years hence and says "Give me my gun back, please," or "Please deliver my gun to George," and Fred or George isn't licensed, what are you going to do? For this reason, the receipt should go one to say that the recipient will, whenever so directed by the owner, deliver the weapon to any person who possesses and displays a valid and outstanding license of the class necessary to possess such weapon, and not otherwise.