Yes, it's been covered several times before. Just search for keyless. This thread has it all:
Keyless Entry on Base Model
But the short summary is that the 2009 Base Fit already has all of the parts built into the car for keyless entry. All you need is the transmitter key (you'll find what to get and where to get it in the other thread). You don't need the "Keyless Upgrade Kit" - just a spare key for the Sport model which is cheaper. You can program that key yourself to unlock your car remotely, but if you want that same key to start the car, you'll need a dealer to cut and program it.
If you haven't already bought your new Fit, then negotiate with the dealer ahead of time to do that cutting/programming. He'll likely agree to do it for free because he can hide the cost under new car prep/checkout.