you got very lucky, as your 04 was produced in the latter half of the year and you do have bluetooth, the passcode for pairing is 1049, just hold down the phone key (the face) on your steering wheel when you turn on the car and it should say activate phone, then you will put your phone in pairing mode and it will find the car and ask for the key, which is your PK.

this is how i paired my car's bluetooth, but there are many variants of how to do it depending on what year your car is and what options you have, so if this doesn't work report back and hopefully someone will have a solution.