I imagine paraphernalia to go along with it, such as a leather harness that the woman straps around her waist and that straps onto her sissy's neck. She is then able to lock the sissy in place between her thighs - locking your mouth onto her heavenly pussy. The device might have some sort of lever or winder that allows her to adjust the pressure on you.
Can you imagine spending a whole morning clamped between her thighs (see below) as she commands you to pleasure her and squeezes you half to death.