How to read/write an 'address' from a memory location......

I am trying to read an address from a memory location and then write
into that memory location.
i.e.
<i>
unsigned long * mem_pointer = 0x93700020; //Valid memory location on
my hardware
unsigned long mem_value = *mem_pointer; //Retrieve the value (another
memory location) from
//the
pointer
</i>

The question is - How do i use the value at <i> mem_value </i> as an
address? Basically, I want to do something like.
<i>
*(unsigned char *)mem_value = 10.
</i>

Thanks and warm regards,
Rintu

.