Okay, here's how I do it when I have to or if someone wants to see the inside of the phone and how red it really is.
Steps:
1. Place your fingernail, a dime, or anything that fits in the red slit right under the headphone jack, and slowly pry it up until you hear it pop open.
2. Keep lifting up until the top leading edge is now up and revealing some of the insides of the phone.
3. Run your fingernail right along the edge of the back cover, all the way around on every side. It will EASILY (no pushing or cramming needed) pop up, and you can remove the back by simply grabbing it and lifting.
To re-install:
1. Line up the bottom edge with the bottom of the phone.
2. Slowly, just pushing with your thumb or fingers, just keep working your way up to the top of the phone while stopping often and pushing down with enough force until you feel it pop into place.
3. Once it's visibly in place, take your thumb, and while pressing with some force, run your finger along the entire border of the back cover, making sure everything is in place and secure.
At this point, you'll look at the phone and murmur to yourself, "Wow, that was easy! Thanks, foodman, for saving me from buying another OEM back cover!". At which point, I will feel the success through telepathic beta waves, and take a bow.