Let's take it as truth for the moment that emotions are just thought plus physical experience (see earlier post). We know that in meditation we can see thoughts just as they are: thoughts only. So, when we set the thoughts aside (which can be learned to do), all that is left of "emotion" is that which we feel in our bodies.
We know that pain can be controlled through hypnosis. That is, with hypnosis we can increase and lower sensation, we can isolate physical experiences in the body and manipulate them.
So it follows that, using similar dial and dilution techniques from hypnosis, we can increase and lower our emotions (the physical experience separated from the thought), so that we control emotions instead of being at their beck and call and controlled by them.