You basically have to pull out the dash and enough of the crap behind it to get to the core. Then you have to remove enough stuff in the bay to get at the two hoses behind the motor going into the firewall. They can be a pain depending on how they are clamped in. I don't think I had to pull any AC lines when I pulled one out of a parts car, but it was couple years ago.
Here is a link to a version of the writeup I used the first time I pulled a dash. It could use some cleaning up, but it will help you get the job done. I've done half a dozen at this point. Your first one is the hardest because there are so many hidden screws. You can pull the dash without pulling the steering wheel, but You'll need to pull the front seats out and it is still a major PITA. It's worth it to make the trip to autozone/advanced and rent a steering wheel puller. It also helps to have a friend with you to help maneuver the dash.
Also, since you going to have to re-add a lot of fluid afterward, it's not a bad time to flush your coolant system if you haven't in a while. A little maintenance never hurt anybody. You may as well replace the heater core hoses with new ones too, they are a pain to change later IMO.
