I'm looking through my shop manual, it mentions the diagnostic connector in the engine bay but doesn't show a pinout or how to get it to flash codes on the dash, I'm certain you can do it but its only showing me how to use Ford's scan tool with the diagnostic connector.
I'll try find the other part of it, theres another electrical supplement, it might be in there.
EDIT: Here is the pinout of the diagnosis connector in the wiring diagrams, but nothing on how to bring up engine light flash.
Worst case scenario the Festiva Forum boys might be able to point you in the right direction as well:
http://aspire.b1.jcink.com/index.php?act=idx
At a
guess I'd be saying jumper wire between
"GND" and
"TEST"