While possibly related to "channeling" and "mediumship" in technique, the intention here is to open the Conscious Mind to the Sub-Conscious and experience the unity of consciousness as indeed there truly is.
Within that unity—just as there is in the ocean everywhere on planet earth with its layers, currents, variations in temperature, etc.—there will often be practical barriers preventing the free flow of information from the one to the other. Through our disciplines we must do the same kind of thing done with wireless communications technology: establish a channel of our own that is "interference free." We calm the mind through ritual, breath control, meditation, and routine. We isolate our channel from the noise of others and direct it towards known sources.
In studying both channeling and mediumship we can benefit from the cumulative experience of many thousands of practitioners recorded in studies, journals, folk lore, and expositions of theory, practice, and application. With either approach we need to develop means of conscious control.
No matter which approach we adopt, it is what the practitioner does that "powers up" the actual process and this is done with defined intention to establish the channel and then to clear if of all interference. The "channel" may be the various tools, or the tools may only use the mentally created channel. Again, it is the practitioner’s intention that matters.
The conscious mind can create the channel as an act of creative imagination in which a gate, door, natural stream, road of light, tunnel, etc., can serve as an "information highway," or it can just feel the intention itself, or that your own journal will itself serve as a channel (as in dream processing and in automatic writing). Find what has the strongest appeal to you, something that satisfies your sense of drama or propriety.
Clearing the channel of interference is commonly accomplished by keeping the whole operation secret, or revealed only to a group of supporters so that no expression of amusement, criticism, contrary images, or doubts interferes with your own sense of correctness.
The choice of either direct experience or of a divinatory or communication tool will, to some degree, shape the remaining elements of composition, transmittal, receiving and interpretation.