The below posting shows what to look for. The white plug with the yellow (lower left in the picture) usually wrapped in black paper tape, is the keyless entry programmer plug. It was hanging down a bit in the upper right corner of the carpet passenger side, on both of our remoteless cars, so I got those same remotes off e-bay, programmed them, and they work.
http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=trouble&Number=724569&fpart=&PHPSESSID=
Also, there is an actuator on the trunk latch, held with 2 torx head screws, but you have to remove the trunk liner to see. If your car is a Duratec engine, you have a good chance of having the keyless.