ЗЫ Although in the case of bulemic supermodels who throw up
on purpose, I would
guess it's possible to say "Я собираюсь вызвать рвоту" (lit., "I'm preparing to induce vomiting") or something like that? However, in the context of a person who's seasick or drunk,
AFAIK you would normally use an impersonal verb in the 3rd-person-singular with the "logical subject" in the accusative: Господи, меня/её/нас сейчас вырвет -- принести ведро, скорее! ("Ohmygod, I'm/she's/we're about to throw up -- quick, bring a bucket!")