It's quite easily actually. First open the cupholder. Remove the two screws behind it. Then gently pull the coupholder out. Then gently pry the silver plastic from the top right and go down and pull the bottom right out,then bottom left, and then top left last. Then simply remove the 6 screws holding the stereo bracket in, remove factory stereo, connect new wiring, screw new radio into bracket, and reverse the process.
If you've got one of the models without an external antenna(I know 2004's are like this not sure about earlier models) be SURE to connect the power antenna wire on the wiring harness/receiver harness otherwise you won't have crap for radio reception. the power antenna lead powers an amplifier for the on glass antenna. Good luck!

 

Hey thanks for the tip on the antenna. I couldn't figure out why my reception was so bad on the new car.

 

No problem Kuth. I actually had read that but then when I installed my radio I forgot to connect the power antenna. It didn't dawn on me until like a day later so I ripped apart the dash and did it and got much better reception.