I agree with you in that writing about phenomenology is not always easy to access in Gestalt therapy literature. I think Gestalt therapists have a tendancy to write holistically or pragmatically without clear reference to "parts" of theory. Gary Yontef makes the same critique of the lack of clear, cogent material in relation to field theory. I've just put together some readings for our students here in Australia so these might be of use.... I find Yontef to be consistently the most useful and indepth of writers.
Perls, F., Hefferline, R., and Goodman, P. Gestalt Therapy: Excitement and Growth in the Human Personality, Souvenir Press, London, 1972
Chapter III Technique of Awareness
Van Dusen, W. The Phenomenology of a Schizophrenic Experience in Stevens, J.O. gestalt is, Real People Press, Utah, 1975
Yontef, G. Awareness, Dialogue and Process: Essays on Gestalt Therapy, The Gestalt Journal Press, Highland New York, 1993
Pages 181 – 188 and pages 242 - 256