I think it'd be more feasible to have some sort of nanomachine that is able to produce different chemicals, either outside or inside the body. Like some outside input signal would make a solution of nanomachines churn out LSD, a different signal would make the same machines pop out 2C-E, etc. If you could get a stable nanomachine population that could survive long-term in the milieu of the body, then theoretically you could have some control panel, set the dose and push the LSD button, and pretty soon by trippin hard. Even that sort of thing, while definitely plausible, is way beyond our capacity today, and would likely require a fundamental revolution in our understanding of protein folding, intermolecular interactions, the body's internal environment, and a slew of other stuff. Definitely possible but probably still quite a ways off.
When you get into programmable/shared experiences or artificial telepathy, you're talking a whole new ballgame though. That would require a HUGE (and again, absolutely revolutionary) leap in our understanding of how the brain and consciousness operate, and an only slightly less gargantuan leap in our ability to manipulate and design molecules. In fact, it's hard to say whether or not this type of thing would even be at all possible, precisely because we have only the slightest, most rudimentary understanding of how the brain/consciousness operate.
