I was wondering, can you? Say you conjure up.....I dunno, bowser/Daniel Craig/Mickey mouse in your dream and tell them that they are your dream guide.
Would they say OK, and actually be your DG. Would they say yes but be lying, or would they refuse.
Maybe a more experienced LDer could try this out, and see the resultz.
p.s. Maybe you could give them an amulet/necklace to wear which makes them your drem guide