By the way, we teach both of these memory techniques in our presentation skills classes. However, almost no one who comes through our classes ever uses either of these techniques. The reason why is that, if you design a really good presentation in the first place, you won't need to memorize anything. The technique that we teach in our classes is to focus on just a few, key concepts related to what your audience wants or needs to know about your topic. Then, create a visual aid with just those key bullet points on it. Since your bullet points are right there on your slideshow or visual aid, you don't need to memorize them. Then, for each of you bullets, come up with a compelling story, interesting analogy, or some other type of "attention-getter."
If you prepare and practice a few items like this for each of your main bullet points, then, when you deliver the presentation, just internally ask yourself, "How can I best explain this concept to my audience?" The answer will always be one or more of the items that you prepared.
A presentation like this will be much more spontaneous and interesting than a memorized presentation.