[boost] [Boost.MPI] How to use with processes on different machines?

Hi, I would like to know, how i can use Boost.MPI for IPC between different PCs. It is described in the introduction: "Unlike communication in threaded environments or using a shared-memory library, Boost.MPI processes can be spread across many different machines, possibly with different operating systems and underlying architectures." Is there an example, how its done? I cant find one. Or isn't implemented yet? Kind Regards Manuel Jung