The first time I discovered this ability I rather stumbled into it. I was talking with a potential submissive about understanding and controlling her body so that if she became "mine" she would be able to pass that control on to me. By phone, I was walking her through an exercise (for lack of a Read more… better word) to recognize her body's state of arousal, then proceeded to direct her to repeatedly change that level of arousal with no physical touch. Through a combination of focused direction and edging, we were able fairly quickly bring about a rather large orgasm. I am intentionally vague about a few of the steps I think were key in progressing from a completely mental orgasm to "climax on command" because I am debating writing a book on the subject and that information is unneeded here to answer the original poster's question.
Surprisingly, unlike what most of the comments above are speculating, in my experience it does not take years or even months to bring about either a completely mental orgasm or to train a submissive to climax on command. Yes, that even includes forced orgasms via one "trigger" word, but I will get more into a "trigger" later. With both of the submissives I tried this with, it happened the first time within a couple hours converation. To date, I have never tried it with a dominant woman because at its core I believe this is an act of submission and I am not sure it would work the same.
The submissive mentioned above was also in the middle of finals for a very time demanding degree at the time, so she was excessively tired from overwork and sleep deprivation. I am not sure if this helped ensure the ease of training, but I believe it might have contributed to it. I asked her how many orgasms in one day was her current record before talking with me, to which she answered six. I will admit that I was a bit like a child with a new toy upon the discovery of the ability to induce an orgasm with only a command and by the time we were saying good night many hours later the new record was somewhere between 140-160. I can't remember the exact number since it was almost five years ago.
We spoke many times as I was a way to help her calm down and be there for her when she was stressing over the exams, and I played around with my new control over her in new and entertaining ways. It quickly progressed from her climaxing when I told her to, to climaxing at a one word command. At one point, she fell asleep on a couch studying while still on the phone with me (I would often play video games while talking with her to keep her company in this stressful time), and as she was still lightly communicating with me in her sleep, I decided to test out to see if it would continue to work. It did. Over the next half hour I proceeded to repeatedly command her to orgasm only to be met by little whimpers in reply. After the half hour passed, I told her to wake up so she could get back to studying, to which she groggily yet promptly did and excused herself to run to the bathroom before she got back to it. Over the receiver I then heard a loud, "What the FUCK?". Apparently, as she was repeatedly orgasming while laying on her side with her legs together, she had essentially filled up with juices that had drained out when she stood up, much to her surprise. (There is more to that story, but again... I will save it for the book.)
I added that information as a response to the people reading this and mentally demanding, "If you were on the phone, why would you believe that she is actually climaxing? Don't you think she was faking it?" This was one example of many that quickly changed my personal disbelief and skepticism into a view more open to the idea of trained and forced orgasms. Another situation and learning experience that helped convince me of the potential validity of this ability happened about a week later. I was looking to surprise her so I opened a phone conversation with the first word commanding her to orgasm. I heard the expected yet anticipated moans in response, then was met with, "Fuck! Sir, I'm driving." Fortunately, she was at a stop light at the time, but I decided that it was a bad idea to blindly force someone to essentially lose a bit of control of their body without knowing it is safe for that person.
After a few months, we grew apart as she was a submissive entering the workforce and I was seeking a live-in slave. About a year later and after many long conversations with various potentials, I decided to bring one with whom I felt a connection into my home. Again, using the same method, mental orgasms were quickly achieved and immediately progressed to climax on command. As she essentially turned out to be less of a slave and more of a pet, I often brought her out with me to run errands, see movies, visit game stores and accompany me antiquing. In answer to the original poster's question, yes. It is not only possible to bring about an orgasm with the use of one word, it is actually pretty fun to be walking down the isles of Home Depot looking for a new tool or a needed piece necessary for a renovation and with a word turn the smiling, bouncing, bubbly little thing next to you into a shuddering, melting mass hanging off your arm for support.
I believe it is important to get across though... In my experience, it is not about a "trigger word". It is about conveying intent. I have been able to train multiple submissives to climax on command both in person and remotely. It doesn't matter the word as I have brought about orgasms by simply saying "now" and even with nothing more than a meaningful glance. It is less about conditioning a word and more about conditioning a spirit. From my experience, it is about submission and control.
I hope that helps.
-d