Who is John and Tom McPherson from Out on a Limb and what is their importance?

John and Tom MacPherson are two of Kevin's four spirit guides. John is an ancient spirit who speaks in Biblical English, often using language that is so difficult to understand that he stops speaking and allows another spirit to come out. Tom MacPherson is once an Irish pickpocket who chooses to continue with that persona from the spirit world because he so enjoys that particular incarnation.