JqPlot - How to add a vertical scrollbar to a legend field containing many legend items

Last week I asked the following question, to which I received an answer:

jqPlot - pie legend is too high when there are many legend items

Now I’m looking for a way to add a vertical scrollbar to the legend field, which in some cases can contain more than 20 legend items.

I can achieve the result that I want in FireFox and Chrome if I add the following settings to my CSS file:

table.jqplot-table-legend {
    display: block;
    height: 350px;
    overflow-y: scroll;
}

however, I need to achieve the same effect in IE9.

Does anyone know what CSS settings I need?