Multiplication of Categoricals in ForneyLab

I am trying to implement the skill modeling in Chapter 2 of Model-based machine learning by Winn and Bishop. In the course of the model, I create a factor node that is the product of two categoricals. I found out that this type of node is not implemented in ForneyLab. Before I consider extending ForneyLab, which is currently beyond my abilities, I wondered why this was not implemented, given the complexities of the library. Was it simply that nobody required the functionality, or is the implementation expected to be complex? Thank you!