This free pdf Psychonauts Journey describes UFO's and extraterrestrial aliens as astral phenomena arising when the human psyche explores the cosmic dreamtime of the universal consciousness. It also contains instructions in a method called Shared Interactive Visualisations whereby a group may conduct such astral explorations via collaborative use of active imagination.

Code:
http://www.lulu.com/items/volume_68/8996000/8996684/1/print/8996684.pdf
I found it interesting and useful - especially when combined with lucid dreaming and astral meditations. I hope it will be of use to you to.