I don't know exactly how the wiring was done, I got mine done by a shop.
I did however find this article online:
http://gonzo777.home.insightbb.com/d...arkersdiy.html
It's not a Civic but the pics shown looks EXACTLY like the steps my installer took. Even the hole that is shown in the link is cut exactly the way mine was. As far as the wiring goes, not sure but looks like it's the same as well.