New Stereo

Just a question to see if anyone knows I have a 2002 Grand am Se1 has the factory stereo still in it. And I am wanting to put in a Alpine deck with new speakers and prolly an amp also. Besides installing the system into the car what else needs done to it for it to work. I have read all the posts about this and seems like it is the 03- newer vehicles you have to put the deck in the trunk and wire it up. Just wanting to make sure that with an 02 you don't have to.

Thanks in advance.