i've read accounts of people that are envenomated by black mambas and cobras and survive w/o antivenom... from what i remember the doctors did exactly what you said. if they could be kept alive on a ventilator and their fevers kept down then there's a chance for survival.
then again, some venoms do even worse things to ya... like make you bleed from every orifice or permanently damage blood vessels and tissues. i'm not sure which snakes do what off hand... a lot of snakes have venom that does more than one thing - like a cocktail of venoms.