Creating a smooth scrolling MC containing btns

Hi all,

Creating my own navigation pane by using a movie clip that contains btns.
This navigation pane is quite long, many btns, so I have set it in a mask and now I am trying to make it scroll smoothly, vertically.
This is what I have managed to get working so far:-

up_btn.onRelease = function() {
navBar_mc._y -= 2;
};

(Obviously down is opposite to that)

However, what I want to achieve is something like:-

up_btn.[COLOR=“Red”]onRollOver[/COLOR] = function() {
navBar_mc.[COLOR=“red”]scroll[/COLOR] -= 2;
};

Obviously the above code is incorrect but it gives you an idea what I am trying to achieve.
Once I have made it scroll up and down successfully, I assume that I would have to code in some boundaries for the mc boundary.

Any help would be much appreciated.

Cheers,

Dave