How Can I Use the Action Actuator On a Cube?

It doesn’t seem to work when I select the actuator as an action, and fill in all of the boxes that are neccessary.

the action actuator is for armatures only. You can rig the cube and use the actuator on its armature.

An IPO actuator is probably what you’re looking for, though. Or a motion actuator.

Why can’t I see IPO?

If you’re using 2.5x I think they changed the name, of F-curve or something.