You basically have to use the high level outputs coming out of the sony amp, which is located in the trunk or rear hatch area under the spare tire cover in the upper left hand corner of the foam spacer block.
Give this thread a read it will give you a jump start on wire locations
Wiring Guide for the Sony 10 Speaker Amp?
The focus only has one center channel (in the front) and one sub, hence the 10 speakers versus 12 in the fusion, and the wire colors are most likely different.
Most likely you will not have to rip into the dash at all, just the doors and trunk or hatch area.