Meclazine does bind to D1 and D2 receptors, but don't forget that there are dopamine receptors feeding from the vestibular system which regulate acetylcholine. The binding of meclazine to these vestibular receptors probably produces a synergistic effect (in addition to the primary mechanism of action on the histamine H1 receptors) in reducing ototoxicity (emetic input from the vestibular system - as in motion sickness), but it's of limited relevence to the dopamine and serotonin receptors fed by vagal afferents (emetic inputs from irritants in the stomach and intestines), or the CTZ.
That's a slightly over-complicated way of saying that Meclazines anti-emetic effect is of limited to no use with the SN method.
Although as a side note, if you're especially prone to vomiting and availability isn't a problem, a three drug anti-emetic combo might be the most effective - metoclopramide, ondanseron and Lorazepam. For most people that is serious overkill, and it's definitely not mandatory, but as I say if you have a very sensitive vomit reflex, can see vomiting being a big problem, and can obtain the meds - that might be the way to go.
Having said all of that, I know very little about SN as a drug so I'm going on general assumptions here. Also writing this when very tired so I apologize if there are any glaringly obvious errors