Horizontal Scroll Bar for New Products

I'm trying to add a horizontal scroll bar to the New Products centered box. The width of the box is 400px, which fits 3 items at the default settings.
The 4th item is wrapping around, so I tried overflow: auto to a new CSS line for .centerBoxWrapper, overflow: scroll didn't work either. (new install of v1.3.8.)

Can anyone help?

I know there are scroller addons but I'm just looking for a manual scrollbar. Thanks.

you need to set fix height for your new product center box for scroll bar to work

you can try this and change value as you need.
add this to your stylesheet.css

#whatsNew {
overflow-y: scroll;
height:150px;
}

base on many threads i read on different forum , it is not recommended to add scroll bars to div .

This works for scrolling vertically, but I'd like to scroll on the x horizontally so my products will go left to right.

Why is it bad to put scrollbars in a div? Is there something else I can do? i.e. there would be 10 new items, but only want to show 3 at a time.