How can I use a Z-wave switch as a 3-way with no neutral?
I recently had a 3-way replaced with a Z-wave combination from Leviton (R02-DZS15 and VP0SR-10Z). The switch requires constant communication with the hub and thus needs power. If you look carefully at the wiring diagram for the Z-wave switches, you will notice that there is a live+neutral powering the switch and a circuit breaking wiring to the light to turn it on-off. Thus, IMHO, you cannot have a Z-wave switch without a neutral wire. Fortunately, in my case there was a neutral wire in one of the boxes and the electrician was able to pull one to the other box. 

Trust me once you set the z-wave switch with a hub and program it to work, the additional cost of fishing a neutral wire will be really worth it.