Have a look here. While the original poster did not follow up with me after a certain point on (and so we do not know if it ever worked or not), the approach is the same as I specified there, and should work as long as you follow the incremental steps:
- find a working C/C++ library for Linux. Failing that, get one for Arduino and port it over (more time consuming)
- use the library in a stand-alone program (hopefully there will be an example with the library itself) to verify everything works fine
- following the library's documentation (and/or the C/C++ example code that comes with it), write a minimal regular C++ Bela program that uses the library and make sure it works ok
- at that point, integrate such code with the libpd wrapper (see here) and you are done
Granted, this is not necessarily a piece of cake, especially if you are completely new to C++, however it is not impossible, and we are here to help at each step!
My first post in the thread linked above should give you all the details you need to get started. Let us know how you get on!