Here is one version of the antenna adapter, there are others out there, but this one is $4.99 from Crutchfield.
as fas as changing the pins around, the adapter that I got you can just bend the pin to one direction a little and then pull the wire side and it pops right out, straighten the pin out then insert in correct location, it will "click" into place. They do make a "pin removal tool" but its not really needed.
Here is what the harness looked like for my car. I tested each wire on the factory harness before I started and would recommend doing the same before applying power to anything. Easy way to test is:
12v constant (always on) - Use a test light for each wire will car is off. Only wire that will have power is the 12v constant.
12v switched (or accessory) will have power when you turn the key (12v will still have power so test for that first and mark before doing this step)
Ground - use test light on 12v constant that you found in step one and then move ground side of text light to each wire until you get complete circuit, that is your ground wire.
Illumination - Turn lights on car and wire will only have power when lights are on. (12v constant and 12v switched will also have power at this time, so make sure they are both marked at this point)
As far as the speakers go, you can use a 9v battery to text these, you will hear the speaker pop if you have the right 2 wires for the speaker you are testing.
I dont have a before picture (sorry) but some places may sell a slightly different harness (may have blue wire for amp turn-on or power antenna), but for my install and my harness, this is all that is needed. I would be more then happy to walk anyone through these steps on the phone or re-pin the harness locally/by mail for free. Also, if anyone is local and wants help installing a stereo or system, I dont mind helping out. Also, I want to note that I dont listen to the "radio" at all, so I didnt look into getting a powered antenna adapter or wiring it up that way. I only use my radio to play my Sirius and iPod.