I used the remote antenna wire for my loc. Fuse would work too though.
LOC in the trunk would be easy if the new Focus would have speakers there. But seeing it doesnt, it would be more work installing it there and then running wires from your doors to the trunk for the LOC and then run wires back again to the door from the amp.
2012 SE Sedan Spec 201A, Sport appearance package and 17" wheels