EDIT: N/M I Found a solution.

I have a moving platform code.
I set Alt.Value A (Velocity X) to 2, and Alt.Value B (Velocity Y) to 2 as the initial #'s for the moving platform.
I have 4 detector objects. They are [up], [down], [left], [right] detectors.
Say for example, the platform moves right. When it hits [left]. I want it to move the other way. If it is moving left, and hits another [left] detector I want it to keep moving that way.

On the map, the moving platform detectors are set up like this.
[right], [up], [right], [down], [left], [up], [left], [down]
You get the idea.

In other words, how can I make the alterable value change from a positive to a negative when I want to, and keep it a negative until I want to change it into a positive?