How can I programmatically configure "Packet Output" and "Packet Input" blocks from the SLDRT toolbox?

I have created a custom Simulink library with blocks that interface with external hardware via USB serial using the "Packet Output" and "Packet Input" blocks from the SLDRT toolbox.

I would like to set the COM port and baudrate on model startup using a callback that will query the available serial ports and configure the packet blocks appropriately.

I have investigated usage of the find_system and set_param functions but I cannot figure out how to acess the properties representing COM port and baudrate.

Any help or guidance would be greatly appreciated.