Mahavatar Babaji re-introduced this ancient technique in 1861 and gave permission for it's dissemination to his disciple Lahiri Mahasaya.
In order to prepare for the practice of Kriya Yoga, the Yoga Sutras of Patanjali are to be studied,
the Eight Fold Path learned and adheared to; the Bhagavad Gita is to be read, studied and meditated upon; and a Disciple-Guru relationship entered into freely with the Guru who will initiate the disciple into the actual Kriya Yoga techniques. These techniques themselves, given by the Guru, are to be done as per the gurus instructions for the individual.