How to chant the Narayana-kavaca shield

Expressions researched:
"One must then chant the mantra of six syllables" |"one should chant the mantra composed of twelve syllables" |"one should first wash his hands and legs clean and then perform acamana" |"one should think himself qualitatively one with the Supreme Personality of Godhead"

SB Canto 6

SB 6.8.4-6, Translation:

Viśvarūpa said: If some form of fear arrives, one should first wash his hands and legs clean and then perform ācamana by chanting this mantra: oṁ apavitraḥ pavitro vā sarvāvasthāṁ gato 'pi vā/ yaḥ smaret puṇḍarīkākṣaṁ sa bahyābhyantaraḥ śuciḥ/ śrī-viṣṇu śrī-viṣṇu śrī-viṣṇu. Then one should touch kuśa grass and sit gravely and silently, facing north. When completely purified, one should touch the mantra composed of eight syllables to the eight parts of his body and touch the mantra composed of twelve syllables to his hands. Thus, in the following manner, he should bind himself with the Nārāyaṇa coat of armor. First, while chanting the mantra composed of eight syllables (oṁ namo nārāyaṇāya), beginning with the praṇava, the syllable oṁ, one should touch his hands to eight parts of his body, starting with the two feet and progressing systematically to the knees, thighs, abdomen, heart, chest, mouth and head. Then one should chant the mantra in reverse, beginning from the last syllable (ya), while touching the parts of his body in the reverse order. These two processes are known as utpatti-nyāsa and saṁhāra-nyāsa respectively.

SB 6.8.7, Translation:

Then one should chant the mantra composed of twelve syllables (oṁ namo bhagavate vāsudevāya). Preceding each syllable by the oṁkāra, one should place the syllables of the mantra on the tips of his fingers, beginning with the index finger of the right hand and concluding with the index finger of the left. The four remaining syllables should be placed on the joints of the thumbs.

SB 6.8.8-10, Translation:

One must then chant the mantra of six syllables (oṁ viṣṇave namaḥ). One should place the syllable "oṁ" on his heart, the syllable "vi" on the top of his head, the syllable "ṣa" between his eyebrows, the syllable "ṇa" on his tuft of hair (śikhā), and the syllable "ve" between his eyes. The chanter of the mantra should then place the syllable "na" on all the joints of his body and meditate on the syllable "ma" as being a weapon. He should thus become the perfect personification of the mantra. Thereafter, adding visarga to the final syllable "ma," he should chant the mantra "maḥ astrāya phaṭ" in all directions, beginning from the east. In this way, all directions will be bound by the protective armor of the mantra.

SB 6.8.11, Translation:

After finishing this chanting, one should think himself qualitatively one with the Supreme Personality of Godhead, who is full in six opulences and is worthy to be meditated upon. Then one should chant the following protective prayer to Lord Nārāyaṇa, the Nārāyaṇa-kavaca.