Passing jQuery into the WordPress media uploader

As you mention the media uploader dynamically renders the images “on demand” and there doesn’t seem to be an event one can target to add the class. A gross way to do it is to override the wp.media.view.Attachment.Library.className attribute (before the frame is created) to return the extra class if the model id is in the initial selection. It means moving the ids select outside the open, eg

//Image Uploader function                  
odp_slideshowImageUpload = {

    // Call this from the upload button to initiate the upload frame.
    uploader : function() {
        // Get the id of all the images already in the slideshow
        var ids = $( '#odp_slider_container li[id]' ).map(function() { return this.id; }).get();
        wp.media.view.Attachment.Library = wp.media.view.Attachment.Library.extend({
            className: function () { return $.inArray(this.model.get('id').toString(), ids ) !== -1 ? 'attachment testing' : 'attachment'; }
        });
        var frame = wp.media({
            // etc