After thinking about it for a while now, I came to the conclusion that RS isn't in any way different from visualisation. The mechanism behind it is LoA. It works better than "normal" visualisation for some people, because they don't have resistance. It's not that hard to believe that an ex or someone else would sleep with you, right? So, it doesn't really matter what you imagine. What matters is how you feel while doing it.
"Self-abandonment. That is the secret. We have to abandon ourselves to the state, in our love for the state, and in so doing live the life of the state and no more our present state. And to make the state alive, one must become it."
Neville Goddard ~ The Law and the Promise