Navigation arrow with easing

i want something similar to the project selection effect on http://www.squarewave.us

i have my navigation set up but i want a little arrow (like on that site) to go to a specific menu item when clicked (almost exactly like that site).

do i need to make a separate MC than my navigation MC and just add it to the main stage right beside the navigation? orrr…put the arrow MC into the same movie clip as the navigation MC?

also, i have no clue about what the actionscipt would be…with the easing effect and everything.

thanks in advance…if you need an fla…let me know