Prescriptions antiemetic's aren't 100% necessary, but from all accounts they are your best chance since it's hard to determine how you will react with high enough SN consumption they are your best bet to make it effective. If you absolutely cannot get prescription strength you could try without (but again raises the risk of vomiting and failing).
Your alparazolam and ambien may help you fall asleep, cannot say for sure it's effects in conjunction with SN. They aren't immediate but you'd want them becoming effective the same time as your SN so it' would be a lot of judgement on how quickly they kick and you would have to time it out...would be difficult to say.
