In this lecture from the Manual for Self Realization: 112 Meditations of the Vijnana Bhairava Tantra, verses 24, Swami Lakshmanjoo reveals the correct way of meditation on breath with “so‘ham” mantra.
Dhāraṇā 1
शरीभैरव उवाच
ऊरधवे पराणो हयधो जीवो
विसरगातमा परोचचरेत ।
उतपततिदवितयसथाने,
भरणादभरिता सथितिः ॥॥
śrī bhairava uvāca
ūrdhve prāṇo hyadho jīvo
visargātmā paroccaret /
utpattidvitayasthāne,
bharaṇādbharītā sthitiḥ // 24 //
Ūrdhve is from upwards, movement...
Swami Lakshmanjoo explains a śāktopāya154 practice of supreme awareness of voidness, where one enters in the transcendental void state of Śiva.
This excerpt is from The Manual for Self Realization, 112 Meditations of the Vijnana Bhairava (verse 39), by Swami Lakshmanjoo.

Dhāraṇā 16
Now, he will explain another way of process which is āṇavopāya and sentenced to śāmbhavopāya. That is the thirty-ninth śloka.
परणवादिसमुचचारात
पलुतानते शूनयभावनात ।
शूनयया परया शकतया
शूनयतामेति भैरवि ॥॥
...