Add disabled functionality to PT Pill

gistfile1.txt

ul.pt-pill { display: inline-block; margin: 5px 0; padding: 0; list-style-type: none; height: 18px; cursor: default; white-space: nowrap;
	-webkit-user-select: none; -moz-user-select: none; }

ul.pt-pill li { float: left; margin: 0 -1px 0 0; padding: 0 7px; border: 1px solid #a8b1b3; line-height: 18px; background: #fff url(../images/option_bg.gif) repeat-x; cursor: pointer; }

ul.pt-pill li:first-child { -webkit-border-top-left-radius: 3px; -webkit-border-bottom-left-radius: 3px; -moz-border-radius: 3px 0 0 3px; }
ul.pt-pill li:last-child { -webkit-border-top-right-radius: 3px; -webkit-border-bottom-right-radius: 3px; -moz-border-radius: 0 3px 3px 0; }

ul.pt-pill li.selected { background: #fff; position: relative; z-index: 1; text-shadow: 0 1px #fff; cursor: default;
	background: url(../images/selected_bg.gif) repeat-x;
	background: -webkit-gradient(linear, 0 0, 0 100%, from(rgba(0,0,0,0.15)), to(rgba(0,0,0,0.1)));
	background: -moz-linear-gradient(top, rgba(0,0,0,0.15), rgba(0,0,0,0.1));
	-webkit-box-shadow: inset 0 1px rgba(0,0,0,0.1);
	-moz-box-shadow: inset 0 1px rgba(0,0,0,0.1); }

ul.pt-pill-disabled { opacity: 0.5; }
ul.pt-pill-disabled li { cursor: default; }

.matrix ul.pt-pill { margin: 0; }

pt_pill.js

// https://skitch.com/litzinger/ec7e7/edit-entry-expressionengine

ptPill = function($select){

	$select.hide();

	var $disabled = $select.attr('disabled') == 'disabled' ? ' pt-pill-disabled' : '';

	var obj = this,
		$options = $('option', $select),
		$ul = $('<ul class="pt-pill'+ $disabled +'" tabindex="0" />').insertAfter($select),
		$selected;

	$options.each(function(index){
		var $option = $(this),
			$li = $('<li />').appendTo($ul).html($option.html());

		// prevent focus on click
		$li.mousedown(function(event){ event.preventDefault(); });

		if ($disabled == '') {
			$li.click(function(event, testing){
				if ($li == $selected) return;

				if ($selected) {
					$selected.removeClass('selected');
					$select.val($option.val()).change();
				}

				$selected = $li.addClass('selected');
			});
		}

		if ($option.attr('selected')) {
			$li.click();
			$li.addClass('selected');
		}
	});