void CallProc(char* name, ...)

//inside the library:

//the regular function would be:
//void Func(short a, long b);
void Func(void *pvParams)
{
    short a = *(pvParams + 0); //what the first param would be
    long b = *(pvParams + sizeof(short)); //the second param
    DoSomething();
}
//=====================================================

//the callproc in the app

void CallProc(char *name, void *pvParams)
{
    void (*Func)(void*) = (void(*)(void*)) GetProcAddress(module, name);
    Func(pvParams);
}
//=====================================================

//now to call the function...

struct { short a; long b; } FuncParams;
FuncParams.a = 100; //just an example value
FuncParams.b = 1000;
CallProc("Func", *FuncParams);   

CallProc:

    ; pop the function pointer off the stack and into eax
    pop eax

    ; now call it with the parameters passed in
    call [eax]

    ; restore the stack
    add esp, 4

typedef int (*CallProc)(void*, int);

int (*pointer)(int);

int return = ((CastTo)CallProc)(pointer, 10);