Disclaimer: This is how most cars are wired from the factory, not nesc. the way the Solstice is wired.
Each pair of wires should be the same color for each door, the only difference being that one of the wires will have a black line (or writing on it). Pick either one, call it negative and wire all the speakers in the same manor.
Example: If you are going to call the one with the line on it "Negative", then wire all the negative terminals to the wires with the black line on it.
All of the door speakers will be in phase with each other and there is a 50/50 chance that the Subwoofer will be in phase also. But it doesn't really matter. Read below.
A Note about "Being in Phase": Being in of phase is only important in an enclosed environment (of which our Solstice Convertables will never be considered). Also, its more important when it comes to speakers sharing the same enclosure such as 2 subwoofers mounted in a single box. Here's why...
A speaker cone has 3 positions, Nutral, In, and Out. For this discussion, we'll say a negative pulse moves it In and positive pulse moves it out.
If you have 2 subwoofers mounted in the same enclosure, and give them both a positive charge (think hard bass-drum hit), they both move outward causing and increase in cabin pressure which sounds like a dull thud to your ears.
Now, wire one of the subs backwards and you get an opposite, inward movement on it. At the same time, you get an equal outward movement on the other sub. Since there is no rise in cabin pressure, you don't hear anything (o.k. maybe a little since we're not talking about a perfect world here.) This is considered being Out of Phase.
The effect is similar, although slightly reduced, in an enclosed cabin (solid-roofed car) even you have seperate enclosures for the subs. The effect is even less in a convertable, but it would still be noticible.
All that being said, it is less and less noticible the farther the speakers are apart and the smaller the speakers are (think less displacement of air). It's even less noticible (if even at all) with different sized speakers such as a mid-ranged woofer being out of phase with a low-range subwoofer. Trust me, I have a stereo in my Explorer that you can change the polarity of the sub with the push of a button. It makes no audible difference.
The only time that you'd really want to mind your phase between Highs, Mids, and Lows is in an enclosed competition stereo vehicle where they have delicate instruments there to measure pressure, not quality of sound.