Add custom code before each "step" function call in Embedded Coder

Greetings,

currently I'm developing an application firmware for my custom real-time hardware. Because of that, I want to be able to add a custom source before each "model step" is executed because of my custom device driver handler.

Currently I have the custom S blocks placed inside the model itself and scheduled with Scheduler Editor, and it works, but I want to place it outside the visible model. I've looked at the menues in "Configuration Parameters", but only thing I could find is "Aditional Source Code" that does not include what I need.

Is there a way to place the custom source cleanly without mixing it with the visible model itself?