Well, in for a penny, in for a pound...
I suggest that in addition to writing out the scenario (a story board approach, in a way) that you can include prescribed "procedures" - it isn't widely talked about, but you actually get a prescription for things like a barium enema, colonoscopy, MRI, etc (I once took a doctors prescription directly to an MRI facility and saved myself $750, but that's another story entirely and probably only a turn-on if you are a CPA)
So, mentally separating the procedures from the story and then mixing them back in as I formulated the scene was helpful to me.
I don't know about anyone of the rest of you guys, but that a woman can become so stimulated that she cums without my touching her - well, sorry, but I don't think it gets any better than that. And YES, Ellen, the physical manifestations of this (prodigious quantities of fluid is certainly one of them) are a GALACTIC turn-on.
On another point, I once had a partner (an OR nurse, as it happens) who used to start with standard massage with me lying on my belly on the bed, on a towel for obvious reasons. She would simply provide a standard massage for about 45 minutes. Of course, I knew what was coming, so there was this constant tension created between that knowledge and the vanilla massage in the early going. As she worked on the hamstrings and hips and eventually my glutes, my legs would naturally sort of magically "drift" apart, until she had the access she wanted. This wasn't medfet specifically, and she never actually penetrated me. Looking back this seems very weird to me, but whatever.
However, once she could get to my anus, she would use her fingers to push my cheeks open, and alternate working over my anal opening with the pads of her thumbs. She used a combination of oil and lotion but I don't recall the formula, unfortunately. She would simply work her thumbs over the opening, the ring and the wider area in general, watching my response until (I suspect) I was actually open, and when she was moving across the opening there was a repeated "penetration" not exactly what we (on this site) might consider penetration proper, but an opening and relaxation of the ring or sphincter to a point where it was clear to both of us she could have done anything - anything - she wanted.
As I became more and more aroused, I would gradually spread my legs further and further, and eventually wind up on all fours. Usually by the time this happened, I was so aroused that it was just a matter of time before I would have an extremely exhaustive orgasm.
So what I learned here is that sometimes, as the Bauhaus architects once said, "less is more".
Best of luck, I hope you try this approach to your BF's initiation. You can use the technique over the course of three or four sessions...he may wind up actually asking you to penetrate him. It certainly was helpful to me, and of course the nature of chances not taken does occasionally haunt me.
BANZAI...