Scaling menu so buttons maintain their distance to the scaled button

What im trying to do is turning out to be quite difficult.

I’m trying to make a horizontal scaling menu with 4 buttons. when you roll over one of the buttons it will scale up to 150% and then when you roll out it scales back down. Now, its easy to make the surrounding buttons maintain their respective distance from the button pressed, but what im trying to do is if the second button from the left was rolled over it would scale to 150% and the surrounding buttons would slide out in their directions appropriately. So the first button would slide left, second button would scale up from the center(so both sides move out, _x remains the same), and the third and fourth buttons move to the right and keep their distance.

The trouble i’m having is that all of the buttons have to have an _x value that changes. None of them can be static. Any ideas on how i would do this?