Well for the 2000 to 2004, it is not so simple
For cars that came w/o cruise then later added on that wire harness[s] are different from a car that came with cruise control from the factory. So if one had a non cruise control car [e.g. 2004] and found a junker 2004 that came with cruise from the factory, it is not so simple to switch wire harness easily. [Time solves anything I guess]
The kits were only for 2000 to 2004
I don't know if 2005 was different [I suspect so]
Then your ECU needs to be programmed to enable cruise control.
You will be lucky indeed to find a Ford technician that knows this