I did an install on my 98 Civic Lx and I was able to lift the plastic molding on the sides and place the wire there. I used 4 guage power wire. If you are using something larger you may have issues. Email me if you can't get it to work or you have issues.

If you have a sedan, remove the piece of plastic that covers the center pillar. This will allow you to have a little room to lift the plastic molding on the floor by the seat and in the back. Use a screw driver or something similiar to slide the wire under the molding.

Should be pretty easy

Good luck