I guess you may want calculating the thermoelectric properties for a particular crystallographic direction(s). If you go through the following tutorial,
http://docs.quantumwise.com/tutorials/ag_au_interface.html?highlight=device, you will then be able to build any device of your interest for bulk fcc-BN, including BN-based devices with metal electrodes.
To study the properties of pure bulk BN, one may just use BN for the right and left electrode, meaning that you study an imaginary BN-BN "interface" instead of a real interface such as the Ag-Au interface discussed in the tutorial.
Note that you do not need to follow the tutorial straightforwardly as you may build this kind device in the Builder by adding bulk fcc-BN from the Database to Stash, and then use Builders -> Surface (Cleave) (choose the desired crystallographic direction) -> Define surface lattice (keep it as it is) -> Finalize output configuration (set thickness to what you need to have two BN electrodes and central region of BN) -> Finish, and then use Device from Bulk as discussed in the Ag-Au tutorial.