Hi @swingo and thanks for the link!
Unfortunately we do not offer the feature you need at the moment but you can work with Heat Transfer if that suits your application as a first step.
Regarding your question for OpenFOAM it is not possible to implement own code into the platform. If you have any specific wishes please post your query in the Vote For Features section. I think that there are some other users encountering the same issues and have the same request. Please let me know if you have any further questions!
All the best!