That is another way to deal with IR. I’m not personally familiar with it, but if the Harmony has the IR commands for Bartok, then you can use that to learn the commands, instead of borrowing the dCS remote from a dealer.
Either way, you need to get the IR commands into the C4 controller and programmed for C4. Then run the emitter and wire to the front of the Bartok.
As noted above, if your programming is simple consider serial. I have used it and it works, so long as you are only trying to apply simple Bartok commands with one device that has volume controls.