Michael,

What pins are you using for the address lines?
If you are using the standard address lines, it is going to be tough to simulate the !RD and !WR lines. Are the !RD and !WR lines dedicated, could they serve a dual purpose? I have used !RD and !WR to do multiple tasks in a previous project. Although it required me to bring both !RD and !WR to the HIGH state before reading and writing from an external memory device. I am not recommending doing this, only if you cannot redesign because of budget or time contraints. The reason I am not recommending doing this is because you have to remember to bring both of these lines to the HIGH state before a read or write, which is a nightmare in terms or maintaining the code.