The Remco Towing website does not have a listing for the S2000 (odd!) but since it is a rear drive, manual transmission the odds are good that it is towable without mods. Good odds, but not 100% assured. If it is, then 4-down or dolly will work. If not, neither works without a drive shaft disconnect installed.
Hopefully somebody here has researched this and can give you a definitive answer. If not, maybe a Honda dealer can help. Also check the owner manual for any towing advice. If they limit towing to 25-50 miles, for example, that's a bad sign.