Pull the plastic panel under the steering column off by pulling back on the top of the panel. It's held on at the bottom by 2 C shaped channels that fit over 2 plastic posts. The posts are part of the 2 panels on either side of the panel under the steering column.
Just lift the panel off the posts and it's off. The fuse panel is behind the plastic panel under the steering column. FYI-there are several unused circuits in the fuse panel (in case you want to run some additional accessories).
look on pages like fourty four or fourty five in the 08 focus book. It will have a diagram of it and tell you what it actually is, from there you can decidedd which you wanna piggy back off of. Only warning is to count the right one flip the book upside down cause thats how you will see the fuse box