Possibly not. A high school kid where I live died of a caffeine overdose during a caffeine powder eating contest with his friends (yes, really). He wasn't taking antiemetics or even trying to die, and did all the same. (And of course, his parents then lobbied to get caffeine powder banned for sale in my jurisdiction.)
That said, vomiting is a common symptom of severe caffeine overdose (as with most any chemical overdose - vomiting is one of the body's natural, involuntary defense mechanisms), so an antiemetic would seem to be advisable, even if this method is not - it's reportedly quite painful.