Make one. The Focus does have a few holes some people would have you use, but it isn't wise to use existing holes; at lease ones with existing cables or wires. I've even seen suggestions about using an ice pick to start the holes! Bad idea.
Drilling isn't all that difficult. the most important part is making sure what is on both sides of the sheet metal. That, and using a proper grommet for the hole. As for the size, a 3/4 inch is about right for standard harnesses that have in line fuse holders. If you take those apart, they'll easily go through a 3/4" hole. Feed from the cabin side for obvious reasons. Don't forget to put the grommet on the cable first.
If you need more info, read the Wiring article on my web site.