I have three relays running Hardened BSD hosted at Frantech. They do not offer support for setting up IPv6.
By Frantech do you mean buyvm.net ?
If it works the same way as buyvm, your VM should have a single public IPv6 address. You can request a /48 or /56 prefix to be routed to that public IPv6.
Or do you actually need help to have it setup on Hardened BSD?