i was right. a line out converter is required. i hooked up a buddy of mines system to his factory unit so i did have to use the line out converter. he had subs with his amp so i wasnt so sure if this applied to you as well.
but basically your amp will need to have the RCA inputs, as well as speaker level or high level inputs. most amps will have a high level input on the side, but some do not. a high level input will allow you to tap into the signal from stock deck output, and hook directly into the amp. this is the easiest way, but will often give the worst sound quality of the options I give you. a Line Out Converter will allow you to tap into the signal at the back of the radio, and convert the signal to a low level or RCA output. By doing this you will help to reject some of the noise that would be picked up between the stock radio and stock speaker.
All the power wires to the amp will be ran the same with the exception of the remote turn on wire. +12v constant will still go to the battery(properly fused with 12" of the battery!), and the ground will still go to the chassis. You can hook the remote turn on to the +12v ignition wire behind the radio, or the equivilent fuse in the fuse box. I would not recomend hooking it up to the pwr ant wire on the stock deck as it often goes off when the radio is off, or cd is playing.