I want to preface this with the following statement. Although this does what you want.. it's quite ugly. This is more in line with what you were assuming you could "just do" with C#.. when in fact it's much harder.
unsafe {
int* a = stackalloc int[1];
int* b = stackalloc int[1];
*a = 10;
*b = 20;
int*[] rihanna = { a, b };
for (int i = 0; i < rihanna.Length; i++) {
(*rihanna[i])++;
}
Console.WriteLine("{0} {1} ", *a, *b); // "11 21"
}