Lower Tan Tien Breathing
Kidney-1 Breathing

The following links cover a lot of ground re: integrating lower tan tien breathing with the Kidney-1 acupoint.
RELATED LINKS
Distal Acupressure Massage - activating the arms and legs through acupressure, including K-1 and PC-8. Physical massage of acupoints activates the channels, jump-starts toward more meditative sensitivity. Often over-looked, immensely helpful. Part of the short set of massage essays.
I find that the K-1 acupoint is most effectively massaged by using a bonger.
Exploring the Exhale - read through to "Variation #3: Perineum Lift - activating Hui Yin". An activated hui yin connects the lower tan tien to the feet, K-1.
Palm and Sole Breathing - The practice of breathing through K-1 and PC-8, as related to Iron Shirt packing breathing. Written by Dr. Jampa Mackenzie Stewart, D.O.M., L.Ac., and Senior Healing Tao Instructor. Palm and sole breathing, through K-1 and PC-8, is a standard Taoist practice used in standing meditations (zhan zhuang).
Center-based Shen Theory - Shifting consciousness into the lower tan tien through sustained, relaxed K-1 breathing.