Is it possible to set output width of a C S-function block from parameters?

I am implementing a simulink model with which I would like to associate a C file. Therefore, I have added a C S-function to the model. The output width of the block is variable from a simulation to another. However, it remains constant during an instance of a simulation. Now I intend to feed the output width as a parameter to the block. Eventually, a GUI will be provided which modifies the parameter's value. My first question is whether it is possible to set the output width via the block's parameter? If yes, then how? And lastly, is it possible to modify a block's parameter from a GUI?