You can program additional keys into a Ford Fusion from 2002 to 2008 using a manual procedure. To do this you must be in possession of two unique keys that start the vehicle. The transponder chip in one key can't be a copy or clone of the other.
The key programming procedure is available here:
Ford Fusion 2002-2008 key programming
If you do not have two unique keys then a diagnostic machine plugged into the vehicle will be required.
Alternatively... if a key that starts the vehicle is brought or sent to us we have the facilities to copy the transponder chip within it onto a new one. The new key will then start the vehicle without any further programming being required. Email us at email@example.com for further information.