Sliding menu/gallery with PREV - NEXT button

Sarting from this:

http://www.kirupa.com/developer/flash8/slidingMenu.htm

Any idea on how I could implement Next - Prev buttons to the navigation, instead of having to click bt 1, bt 2, bt 3… well, I will leave it but I want to add the buttons as well.

I tried with assigning variables to the content mcs… anyway. I just can’t figure it out.
Here is the Kirupa tutorial file link if you are willing to play with it:
http://www.kirupa.com/developer/flash8/code/easing_source_final.zip

thanks