How do I add variables to Custom Storageclass

I would like to add some variables to my custom Storageclass and save them in my simulink Model. After I generated my model i want to be able to generate C-Code from this model. In this C-Code i Need to save some specific Parameters to signallines, because i like to have the model Independent from my .m Script. This is important for me because i want to be able to Change signals in the model without opening my m-script.