Slider menu in

Hi all,
I’ve followed the tutorial to create a menu with the slider. It works fine but now my problem is not all the button in on my site are the same width (in pixel) therefore the slider with the arrow (like in the tutorial) is not centered below my button. Does anyone know how to modifiy the actionscript to make it that my slider can be centered on every button even if the size of the button aren’t the same width?

thanks for your help