havent tested this out yet, but you can try...
in skin1/modules/Product_Options/display_options.tpl
find:
Code:
{foreach from=$options item=v}
<TR>
<TD>{$v.class}: </TD>
<TD>{$v.option_name}</TD>
</TR>
{/foreach}
change to:
Code:
<tr>
{foreach name=optloop from=$options item=v}
<TD>{$v.class}: </TD>
<TD>{$v.option_name}</TD>
{if $smarty.foreach.optloop.iteration is div by 3}
</tr>
<tr>
{/if}
{/foreach}
</tr>