What kinda button are you going to use? I really like the Ford GT button, found a good deal on it too, normally around $150, found it for $80 with harness. Intended for 05-09 'Stang, don't see why it wouldn't work for a focus though....
Here's the link.
'02 Sedan, Gold, 2.0l 16v Zetec, ICW Kobe Gunmetal 17" w/ Falken ze912
8000k HID conversion, Full SVT Interior, and Suspension
Pioneer AVHP4000, 2 JL Audio 10W6 Subs, 1200W Sony amp, 80GB Portable HDD
Zetec Crew #308