Would a channeled dialog with the deep subconscious, say when the client is sleeping (or even awake) register a change in brainwave activity on an EEG?

As we have mentioned, there would likely be some discernable change in the waveforms, especially during sleep when there is a state of quiescence overall. That would give the greatest chance of demonstrating some tangible evidence of an actual connection with a person's mind remotely by channeling.