Unfortunately I haven't got the mod otherwise I'd help. If there are no settings anywhere within admin, you could then try this...
1. Wrap a DIV around the latest additions table and give it a class "additions"...
<div class="additions">
latest additions table here
</div>
2. In your main css file skin1/skin1.css add...
.additions TABLE {
width:100%;
text-align:center;
}
If you are able to add a class to the table rather than adding DIVs that would make things a little easier.
Hopefully this will give you a start but it might be best to wait for an answer.