I was thinking about the Headless rite from the PGM. Essentially the magician assumes the role of the Headless One in that rite and thus is imbued with that spirit's power for use in whatever working. The magician then goes on to call other spirits using the authority of the Headless One.
I've had some difficulty in reconciling the intermediary's role in the Grimorium Verum workings in my mind. It feels cumbersome for me to call Scirlin in order to induce him to call in the spirit I intend to work with. It occurred to me to take a similar tack as with the Headless One, invoking him and acting as him in order to utilize his spiritual power in calling the spirits of the grimoire.
I will be asking Scirlin about this directly, and I'll share what I'm told, but I'm curious about what y'all thought.