for example, in the case of jquery ui tabs, you can add the classes that jquery ui adds manually.
<div class="ui-tabs ui-widget ui-widget-content ui-corner-all" id="tabs">
<ul class="ui-tabs-nav ui-helper-reset ui-helper-clearfix ui-widget-header ui-corner-all">
<li class="ui-state-default ui-corner-top ui-tabs-selected ui-state-active"><a href="#tabs-1">Nunc tincidunt</a></li>
<li class="ui-state-default ui-corner-top"><a href="#tabs-2">Proin dolor</a></li>
</ul>
<div class="ui-tabs-panel ui-widget-content ui-corner-bottom" id="tabs-1">
<p>Tab one content goes here.</p>
</div>
<div class="ui-tabs-panel ui-widget-content ui-corner-bottom ui-tabs-hide" id="tabs-2">
<p>Tab two content goes here.</p>
</div>
</div>
it would prevent the flicker, and make it look the same when javascript is disabled, however clicking on tabs still won't actually do anything when javascript is disabled.
-- Kevin