This builds on the codeshare Stephen Bell provided for using a custom field with a select. This uses a multi-select and reads back in multiple values and resets them when the contentlet is opened.
/* When page is loaded, copy the hidden field value to the dropdown, initialValues is an array after split */ var initialValues = $("#curriculumAssociation").val().split(','); var iLength = initialValues.length; for(var i = 0; i<iLength; i++){ $("#curriculumAssociation_field select option").each(function(index){ if($(this).val() == initialValues[i]){ $(this).val(initialValues[i]).attr('selected', 'selected'); } });