I muddled through the code and solved the problem. Here's how I did it.
in Modules > comboslider.tpl Change lines 24 - 29 from (basically switch the $defaulttab numbers):
{if $displayfeatured}
<li><a href="#new" {if $defaulttab=="1"} class="selected"{/if}>{l s='New products' mod='comboslider'}</a></li>
{/if}
{if $displaynew}
<li><a href="#featured" {if $defaulttab=="0"} class="selected"{/if}>{l s='Featured products' mod='comboslider'}</a></li>
{/if}
to
{if $displayfeatured}
<li><a href="#new" {if $defaulttab=="0"} class="selected"{/if}>{l s='New products' mod='comboslider'}</a></li>
{/if}
{if $displaynew}
<li><a href="#featured" {if $defaulttab=="1"} class="selected"{/if}>{l s='Featured products' mod='comboslider'}</a></li>
{/if}