Yes, there are, actually several possibilities, one way to achieve it is using M-HN-18 (tcm) or mental nerve (mwm) on the jaw. (mental nerve, comes from mandibular division of the trigeminal nerve(V3)).
“sleeper hold” can also be done by several different ways, and doing it relatively safely.

If knockout technique is applied slightly ‘wrong’, side-effects (nausea, dizziness, pain, vomiting, can occur), but in the case of correctly applied knockout technique is safe – because, (actually knockout is wrong term in here), we should say - to put person fast to sleep (no its easier way to say is KO) That way its safe – like natural sleep.

Yes, correct stimulus (pressure) to carotic sinus (the place where baroreceptors are, these receptors monitor the blood pressure and level of oxygen in blood) can cause knockout, but that it can also cause severe traumas to opponent by changing blood pressure quickly – this can lead to arrhythmia to heart. As a side note, but affecting to ones blood pressure and causing KO by that, causes KO where opponent wakes up usually before even dropping to floor – or right after that. This happens because then body itself knows that blood pressure is normal and ok. But if I use just two fingers to put someone out, and doing it with out carotic stimulus, the person will not wakeup before he’s correctly restored.

I did not follow nor read the link you posted, but I think that this gives some answers to it too…

This is my 0.00000001 cent worth...

BTW - At my website, in training/videoclips/ are videoclip number 9 - its not a grabling KO, but only one technique was delivered, and NO carotic sinus nor ST-9 was used.
Yours in the Arts, Toni Kauhanen