Legacy Code Tool and Simulink Builder Block for C++ Structs and Classes

I have C++ code containing both structs and classes. I need to be able to call the functions in these classes with the structs as inputs/outputs into a function block to use in Simulink. What is the best way to go about this?

I know the s-function builder isn't supported with C++ and the documentation states that the Legacy Code Tool can't handle C++ objects.

It states: "Can interface with C++ functions, but not C++ objects. One way of working around this limitation is to use the S-Function Builder to generate the shell of an S-function and then call the legacy C++ code from the S-function's mdlOutputs callback function."

Is there an example of this or what is the best way?

Thank you.