Head Unit Installation for 6 Speaker System, Hate Asking, but I gotta Options

[Fastbird]

I've searched all around the forums and can't seem to get a clear explanation, and the "how to" from the home page of the website cuts off right where I need the info. All the posts I find say "locate the harness' from the factory amp" but what do I do with it??

I'm about to install a Kenwood DDX 8017 into our 99 Celi. Our car is equipped with the six speaker soundsystem with the single amp located under the HVAC controller.

Now, through my searching I've found semi-conflicting posts concerning the use of the 87+ Toyota harness. So my first question is this: If I purchase the 87+ toyota harness, will it work, and which connectors do I plug it in to??? The connectors at the back of the stereo, or the connectors to the amp under the HVAC. Some posts I've seen say the 87+ harness works, others say it doesn't. I just need to know what harness to get so I can get this thing installed.

At this time I AM NOT INTERESTED in running my own wiring from the head unit to the speakers or anything else. I'm looking for a 100% plug and play deal, just to get the head unit in and running.

TIA.