I did a seat swap few months ago. 02 svt seats in my 05 zx5. Had to swap the wire plugs and seat belt plug. AND ! to take off the leather trim and the cushion from the svt passenger seat to put the weight detector.
It was a pain in the a$$ but for yours. 05-07 seats are the same, your already have the weigth detector in your passenger seat. So, you only need to unplug the wires, take off the bolts and do the swap. When everything done, look at you airbag ligths. If nothing twinkle in your dash, well you got it !
2012 White Mitsubishi Lancer 2.0L : New car
2005 Black Ford Focus zx5 SES : Trade In
2003 Arizonna beige Ford Focus SE : Sold