The Kriya Yoga technique popularized by Paramahansa Hariharananda focuses on a "scientific" approach to spiritual transformation, emphasizing the role of the fontanel (the "seventh fire") and the spine. You can find detailed instructional materials in the First Kriya Practice Guide
While advanced Kriya techniques are traditionally taught only through direct initiation, public discourses and writings from the Kriya Yoga Institute outline several fundamental elements: hariharananda kriya yoga technique pdf
Kriya Pranayama: This involves a specific "short breath" technique (often a 1-2-3 inhalation rhythm) designed to touch the "seventh fire" or highest spiritual center. Pranayama : Breathing exercises to control and regulate