You're asking about a 2nd gen in the 3rd gen section. Maybe someone here has owned a 2nd gen and can better answer you. But you might be able to find a turn signal switch on ebay. I know they have them for 3rd gens. Or check your local junkyard or
Car-Part.com--Used Auto Parts Market. As far as aftermarket parts go, I don't know for sure about 2nd gens, but if they are anything like 3rd gens there won't be much aftermarket support for them.
Try
Honda Prelude Forum : Honda Prelude Forums. They have an active 2nd gen section over there.