hehe. well. I think gm picked a good spot.
except for cars, its on the back in the middle of the roof, the "sharkfin"
but I would think the easiest way, so that water can't wick into the interior (trunk incl), run it through the firewall and choose one side of the hood for it, if its black...it should blend right in with the blue.
otherwise the trunk, but the problem there is that, if you do it wrong, water can wick into there...and believe me, if you've never seen what comes from that...don't start now.
I like scott'* way. not bad.