2002 Sunfire Install Monsoon CD

I saw a similar posting, but have more questions. I have a 2002 Sunfire with the original AM/FM/CD system. I have acquired a new Monsoon AM/FM/CD because I had one in an '02 Gran Am and loved it. What modifications do I need to do to install the new Monsoon in my car? I ordered a Delco Monsoon Amp and also need to know where and how to install and any wiring harnesses I need. I also realize I may have wasted a few bucks buying these two items after reading previous Monsoon question. Is it possible to do this changeover and not lose my keyless entry or any other items the unit may control? Guess I am too old and senile to make some assumptions, but maybe someone much sharper than I knows what I should do short of finding a high cliff for the new unit!!