This works amazingly.
It is easy to choose the size for the widget area, I inserted a text widget and put in:
[promoslider width="270px" height="104px" id="widget_promo"
display_nav="links"
]
<style>
#widget_promo img{
width: 270px;
height: 104px;
}
</style>
I needed to add style tags to resize the images to the width and height that I needed in the widget area, because I also used the slider with large images in another area at the same time!