Styling single jQuery UI controlgroup-item - jquery-ui

Question

I am using jQuery UI controlgroup to style checkboxes in an HTML form. After the input values are processed by a PHP script, the results are displayed on the the same page along with the form itself, so that the user can adjust the filters. What I am trying to do, is to have the boxes that were checked previously remain checked after the form has been processed, so that the user sees what selection criteria were used. To achieve that I store all the PHP $_POST data in a JS variable using json_encode, which I'd like to use to iterate through the labels and mark those that were checked previously. The problem is that the only option of the controlgroup widget that I can use is classes with ui-controlgroup-item which shows every single label within the group as active, and for the life of me I cannot figure out how to make it conditional, e.g. so that I can use if(label[for=' + var.value +'])', var being <?php echo json_encode($_POST) ?> or something similar. Will appreciate any suggestions.
Here is the HTML:
<div id="currencyList">
<label for="gbp">GBP</label>
<input type="checkbox" value="gbp" name="currency[]" id="gbp" >
<label for="usd">USD</label>
<input type="checkbox" value="usd" name="currency[]" id="usd">
<label for="eur">EUR</label>
<input type="checkbox" value="eur" name="currency[]" id="eur">
</div>
And this is the JavaScript bit:
$( "#currencyList" ).controlgroup({
classes: {
"ui-controlgroup-item": "ui-checkboxradio-checked ui-state-active"
}
});

Answer 1

After trying to find a solution for several days I decided to skip trying via the classes option and instead to move outside the controlgroup widget. So here is my not-so-pretty-but-working solution:
var postData = <?php echo json_encode($_POST) ?>;
$( "#currencyList" ).controlgroup();
$('#currencyList').children('label').each(function () {
if(postData.currency.indexOf($(this).attr("for")) >= 0){
$(this).addClass( "ui-checkboxradio-checked ui-state-active");
}
});