JS to create a custom Backbone view for managing Soliloquy image meta.

gistfile1.js

// Open up the media manager to handle editing image metadata.
$('#soliloquy-area').on('click.soliloquyModify', '.modify-image', function(e) {
    e.preventDefault();
    var soliloquy_frames        = {};                                       // Store our workflows in an object
    var frame_id                = $(this).next().attr('id').split('-')[3];  // Unique ID for each workflow
    var default_view            = wp.media.view.AttachmentsBrowser;         // Store the default view to restore it later

    // If the media frame already exists, reopen it.
    if ( soliloquy_frames[frame_id] ) {
        soliloquy_frames[frame_id].open();
        return;
    }

    // Create the media frame.
    soliloquy_frames[frame_id] = wp.media({
        className: 'media-frame soliloquy-media-frame',
        title: soliloquy.metatitle,
        button: {
            text: soliloquy.savemeta,
            requires: {
                selection: false // If your frame doesn't require any action to submit, set this to false
            }
        },
        uploader: false // Don't display the uploader since we don't need it
    });

    // Create a new view with our image meta.
    soliloquy_frames[frame_id].display = wp.media.View.extend({
        tagName: 'div',
        className: 'soliloquy-image-meta',
        region: 'content',
        template: wp.media.template('soliloquy-meta-' + frame_id)
    });

    soliloquy_frames[frame_id].view = wp.media.View.extend({
        tagName:   'div',
        className: 'soliloquy-meta',
        initialize: function(){
            this.createMeta();
            this.createToolbar();
        },
        createMeta: function(){
            this.content = new soliloquy_frames[frame_id].display({
                controller: this.controller
            });
            this.views.add(this.content);
        },
        createToolbar: function(){
            this.toolbar = new wp.media.view.Toolbar({
                controller: this.controller
            });
            this.views.add(this.toolbar);
        }
    });

    // Overwrite the default attachments view with our new view.
    wp.media.view.AttachmentsBrowser = soliloquy_frames[frame_id].view;

    // Remove the default routers.
    soliloquy_frames[frame_id].on('router:render:browse', function(view){
        view.unset('browse');
        view.unset('library');
    });

    // Restore the default view when we close the modal window.
    soliloquy_frames[frame_id].on('close', function(){
        wp.media.view.AttachmentsBrowser = default_view;
    });

    // Finally, open the modal.
    soliloquy_frames[frame_id].open();
});

It should be noted that this is grabbing HTML from a custom <div>. You do not have to use script templates like in core. The Underscores _.template function is just looking for an ID to compile into html (using jQuery's html() method), so really anything with the correct ID will suffice.

Also, it is preferable to store your workflows in an object so that you can handle multiple frame states on the same page. I am doing this by using the attachment ID of the image as the workflow key ID. Use whatever you would like as long as it is unique.

Also, the default view should be restored when the modal is closed so that no other media manager frames that expect the default view are harmed. We simply attach to the close event and set the default view.