I love this plugin for exactly the purpose you need it for.
GauVeldt Ease Behavior
Note that this plugin will always place the sprite at the origin point specified. An easy way to make each sprite behave the same way is by doing something like this:
At Start of Layout
For Each Sprite
---> Sprite.GauVeldtEase Set Origin = Sprite.X, Sprite.Y
---> Sprite.GauVeldtEase Set Destination = Sprite.X + 64, Sprite.Y
Then you can do something like...
---> Sprite.GauVeldtEase Ease Both
... and it'll make them go back and forth constantly. Of course it can do a lot more than just that, but I believe that's probably what you're looking for.