You have to take off the whole door panel. Here is a write up from another forum that someone posted in another thread.

http://f150online.com/forums/speaker...s-04-08-a.html

 

I replaced the rear speakers in my supercab and used metra adapter cables. The placement where the new speaker wire connector goes, the rear power window pulls the wires off the speaker, so make sure you wire tie the speaker wires and don't have to take the panels off a second time