I answered my own question, like so:

<script type='text/javascript'>
( function ($, Sys) { 
function HideAllPanels() 
{ 
$('#IDOFAccordionContainer a').each(function(idx, item) { 
$( this ).removeClass('dnnSectionExpanded'); 
}); 
$('#IDOFAccordionContainer fieldset').each(function(idx, item) { 
$( this ).css('display','none'); 
}); 
} 
$(document).ready( 
function () { 
HideAllPanels(); 
Sys.WebForms.PageRequestManager.getInstance().add_endRequest( 
function () { 
HideAllPanels(); 
} 
); 
} 
); 
} 
(jQuery, window.Sys)); 
</script>