Can people be trained into having a certain kinds of dream?
Practically, Dreams are on the realm of the subconscious, or the area of ourselves, which we have less control of.
To a certain extent, we can predict or affect, what dreams an individual might have during his/her sleep. We must identify what are the causes of dreams.
First, Dreams are representations of our mental impulses such as our fears, hopes, desires, worries and goals.
Second, Dreams serves as training ground on how people might solve their current issues, that explains why people think better after a good night sleep.
Thirds, Most parts of our dreams, are forgotten soon after we wake up.
Fourth, Dreams can be presented in Abstract format, difficult to decipher or understand, Or it can be presented in Concrete format, literal or complete representation of our impulses.
So practically, we can predict or affect our dreams by knowing and affecting the causes of our dreams. But we can't predict how our dreams would it be presented upon us, which parts of it, we can still remember(Because maybe you got what you wanted but you just can't remember) or What lesson its trying to teach us.