I, personally, would have to agree with you and your theory. I believe it is possible to alter some one's emotions through a sense of reverse-empathy - per say. I shall explain on two points.
My first point in explaing is the statement of how empathy works for me; which I have known I have the empathic ability for most of my life. But keep in mind that every one experiences things differently, no matter how similar experiences may appear to be similar; or "exact" for that matter. Empathy, to me, revolves around the basis of energies and the various vibration frequencies of energy. (In short, every thing has energy in one form or another. The energyies give off vibrations.) When I make a connection to some one, whether intentional or not, it's more than just a mind to mind/spirit to spirit/physically touching connection, it is connecting my energy to the energy of the person in question. The emotions I have are instantaneously dulled down so that I do not mistake my emotions for theirs. The emotions of the person directly tie into their energy. Meaning that their emotions give off different vibrations of energy; when I connect my energy to their energy I feel these different vibrations and my energy vibrations begin to change frequencies to match theirs; thus, allowing me to feel their emotion. And this lasts until the connection is broken. Once broken, my energy vibrations gradually returns back to normal.
My second point is to explain how the alteration of another person's emotion could quite possibly be accomplished; reverse-empathy as I called it. This requires a few things, I dare say. The first is to have an understanding and a decent amount of experience with basic energy manipulation. The second requirement is to have enough experience with feeling other people's emotions to know the basic idea of what vibration matches what emotion. Keep in mind that energy vibrations that associate with emotions may be similar for most people but never exactly the same. This is why you need substantial experience to know the basic idea of the emotion's energy vibration. And the last requirement would be the most obvious - an empathic connection to the person who's emotion(s) you aim to alter. So, the basic process would be to start by making the empathic connection. From there, decide on what emotion shall be the "new" emotion (if you have not prior decided). Next would be to use energy manipulation to alter/manipulate the original emotion's vibration to match that of the new emotion's vibration, starting with your self. And lastly push that alteration from your self to the person in question via the empathic connection prior made.
Please note that the first step is strictly how I view empathy works and that the second point is strictly theoretical (presently).