Accessing work vectors / simstruc from custom code

I have a level-2 c s-function and it uses PWork vectors for storing data structures.

For some reason I have a separate c code that is inlined to the Simulink model's generated code via the Simulink Coder's Custom Code blocks. This other code runs in a separate task and mutually exclusively to the s-function.

Now in this code I would like to access and manipulate the exact same data structure that is used by the s-function.

Can I do this? If yes, how?

If I include the simstruc.h into my other code, it can in theory call the ssGetPWork(SimStruct *S) method, but my problem is this SimStruct *S parameter. It is passed to the s-function like this in the generated model-code:

SimStruct *rts = <modelname>_M->childSfunctions[0];
sfcnOutputs(rts, 0);

I can put this into my other code, but I would like to do it so, that i do not have to know the name of the model. Thanks for any idea!