there are a few threads on it. your 04 will really not be any different. Sergey (i know i mispelled it but hes not on as much for me to remember) did it with the lesser prep package. he had to install more parts than most of us. I have all the pieces sitting here, but just haven't bought the belt to exchange it out.. so i have not installed it yet.

you cant tell/say if you have the prep package or not? look at the firewall on the passenger side, it there a box with a plastic cover held on the looks like it sealing two hose holes? and then reach in front of the block need the idler pulley (where the ac would go) and see if there is a wire tied up.. and also right near the intake there should be another loose plug.. if you have those three things i think you can install it easily enough.