....Preliminary For The Practice of Trekcho....Shardza Tashi Gyaltsen (1859 - 1933)....An important Bonpo teacher in the Rime Tradition...realized the rainbow body when he died in 1933.....
Go to a quiet place without any people and stay there.First make offerings to the mountain gods or whoever is powerful and spiritual in the area so that they are not disturbed. Tell them where you are practicing so that you do not disturb them.Then, thinking that you must stop desire for samsara, ask what is the purpose of so much attachment? You need to ask why you have this desire.
Imagine that you are naked and born in hell, screaming and suffering as if you are actually there. Then imagine that you are born in the realm of the hungry ghosts (pretas) with endless hunger and want. Imagine you are born in the animal realm, doing as animals do. Then think that you are born as a human with servants—imagine that life; then as a titan (asura) fighting with another—what is the purpose of that? Finally imagine that you are born as a god (deva) and spending life in leisure without thinking of the next life—what is the purpose of this?Imagine that you are circulating from one realm to the next.
Do whatever comes to your mind—in vision or imagination.
Then imagine what it is like to be a yidam (tutelary deity); or that you are in Shambhala and are teaching the bodhisattvas; or in the tantric realms with the siddhas as disciples; or in Sukhavati or Olmo Lungring teaching Dzogpachenpo.Pretend that you are actually doing this.
Finally dissolve all visions into the natural state. What is left? Then dissolve even your thought itself into the natural state so there is nothing left. Then you will realise that everything is made by your thought—everything comes from there. You have to realise how things are created.
You must practice this seriously for at best three months, or at least one month."