so you mean negative= flip image, positive = normal image?
So how about you use float compare + every frame, compare it to 0 to current float variable, is less than 0 = negative, if over or equal 0 = positive.
So the state will have "Get x axis" or watever you using to get the x, and just have compare float right under that state, make 2 events, 1 go negative, another go positive, "swap image", and basically go back to the get x axis state again.