Buttons swap positions

Hi all, I’ve reached the end of my tether with a piece I’m working on and I’m hoping someone out there can help me out. I’m putting together a menu that runs horizontally (I’ve attached a screenshot so you can see what I mean) and I’m looking for a tutorial (or an FLA with some pointers) that will help me achieve the following.
I’d like the menu buttons to move past one another when pressed. IE when button one on the far left is pressed it moves to the position of button three and buttons two and three move back one step. I’m pretty certain I came across a tutorial or thread about this a while back but I’ll be ■■■■■■ if I can find it.
Please help. It’s for my wedding site!