The Fiero uses the same cruise control equipment as any GM car. look for the vacuum cannister bolted onto the trunk wall and see if the vacuum lines and throttle body cable are all there. Best just to look at another Fiero and compare.
From: Lanny
The cruise looks like any GM cruise module - on the end of your wiper control arm (which is also your blinkers, and your brights), there should be a little switch, with three positions. All the way to the left is "off", in the middle is "on", and on the right is rapid acceleration. (you have to hold it in this position - it goes back to on when you let go) There is also a "resume" button on the very end of the control arm. (push "in" towards the steering wheel to slow down)
From: Ryan Wright