Have a look at this:
http://www.focusfanatics.com/forum/s...d.php?t=229873

If you read through, near the end some guy from the UK sussed it.
You don't need an inline fuse. You've got to run a wire from plug 83b on the back of the new focus light switch with fog option you'll need.
Run that through the bulk head or wing into the engine bay, split off into 2 feeds, one for each light, then you'll have to solder some bulb holders to to the ends.
I used the earth points in the engine bay near the battery.