Well, unless you use a helicopter, you do have to go through Limassol as it is approximately half-way between the two cities, roughly on a straight line (or, rather, a slight curve around the mountain). As far as buses are concerned, since the very first time I went to Cyprus, I was amazed by the scarcity of bus lines, both city and outside. Amazingly, only visitors seem to realise that, the locals always suggesting taxis. At any rate, avoid going through Nicosia, it will be a lmuch onger trip.