It is probably worth dropping an email to these guys -
zentrale.ozd-fahrzeuge@ezv.admin.ch
Their website is partly in English, but very limited. But I have found them helpful when I send them an email. You will need to find out details of importing or registering a limited production/one off car in Switzerland. It should be possible to do, because there are these funny little electric/pedal hybrid cars running around town that would not pass any form of crash test. Probably do really well on the emissions though. But these cars are manufactured in Switzerland which may make a difference.