I have tried countless times to force my "subconscious" into dreaming about various people, and it flat out does not work. Telling yourself what you want to dream about is an exercise involving the "conscious" mind, which is more or less shut down to recharge while you're sleeping. Dreams are nothing more than hallucinations; this is why, for example, if you have music playing in the background while you sleep, it will often be audible in your dreams, but usually you will think it is being sung by someone you are talking to, rather than something more reasonable, like a stereo system. Taking hallucinogens with your eyes closed is the same as dreaming.