Firstly I must say, this is a very very difficult proceedure, and even if you know what you are doing, you have to be very gentle. There are a few videos floating around about how to disassemble which I don't recommend following as they make it look far easier than it actually is (oh and don't use a screwdriver like that at all).
One of the better guides I did find was for the 4G version of the phone which doesn't have the tactile home button, but instead it has a full touch keypad. You can see that here. Make note of their use of a heatgun (or a hairdryer) as you will need it to remove the screen from the internal structure. You will also need a Phillips #00 screwdriver, and plastic phone opening tools. Also note that this is NOT a step by step guide, it merely serves to provide some hints.
Following the guide we remove the back cover and panel:
Now we see the culprit, unfortunately it's not as easy as just removing it and putting the new one on. We have to remove the entire screen:
Here is my replacement keypad ready to be installed:
Stick the screen back onto the silver bezel (use a little epoxy in the corners to hold it steady), and put some adhesive tape onto the back of the screen itself (this is to hold the screen to the frame, otherwise it will fall off). If you don't have adhesive tape, you can use epoxy. Also you can now adhere the keypad touch tabs to the screen where they should go (use the bezel as a guide):
I mentioned earlier that you have to be very gentle. Well I managed to do this to the screen when taking it apart (in other words destroy it). I assure you it no longer worked, and it was replaced with a new screen. One thing to note when buying replacement screens, they all seem to be SuperAMOLED (from various forums), even if they say LCD. Even the model numbers are the same as the original. The replacement was also an OEM model, and from a detailed inspection, the only difference is that it doesn't have the Samsung logo, everything else is the same, even down to the driver chips and it looks as crisp as ever.
Once you have replaced the keypad, you will probably notice that the touch buttons don't work. No it's not because you haven't put them on properly (unless you really stuffed something up), instead you will need to update the touch pad firmware to fix this problem. Do this by typing the following into the dialer:
The above screen will appear. Now click Touch key FW update. It should take a few seconds and now your touch buttons will be working once again, along with the dreaded home button :)