Populating fields in "image" dialog...

Hey everyone! This is my first post here.

I'm extremely frustrated with the complexity of a seemingly simple task, and at least 50 Google searches later has proved absolutely no help whatsoever. I want to open the "image" dialog when another event in my application is triggered. Once opened, I want the URL, Alternative Text, etc. to be pre-populated with what I specify. I managed to simply hack the dialogDefinition, which seems super cheezy, but it works. The only problem is the dialogDefinition event only gets fired once, so what I want only works the first time it's used. Here's what I've got:

            // When image is added
            $('#page-image-manager').bind('add-file', function(e, storageId) {
                // Compile image's relative URL
                var url    = '../image?src=' + storageId;
                var markup = '<img $1 src="' + url + '" alt="Loading Image..." />';

                // Open "Image Properties" dialog
                CKEDITOR.instances['page-editor'].openDialog('image');

                // Auto-fill URL and alternative text
                CKEDITOR.on('dialogDefinition', function(ev) {
                    // Get dialog name and definition
                    var dialogName       = ev.data.name;
                    var dialogDefinition = ev.data.definition;

                    // Modify "image" dialog definition
                    if ('image' === dialogName) {
                        // Get "Image Info" tab data, get image URL field
                        var infoTab  = dialogDefinition.getContents('info');
                        var urlField = infoTab.get('txtUrl');
                        var altField = infoTab.get('txtAlt');
                        var preField = infoTab.get('htmlPreview');

                        // Auto-fill "Image Info" fields
                        urlField['default'] = url;
                        altField['default'] = 'Loading Image...';
                        preField['html']    = preField['html'].replace(/<img (id=".*?_previewImage") .*? \/>/gi, markup);
                    }
                });
            });

This feels extremely cheezy, and only works once anyways. What can I do to either fire the dialogDefinition event again, or properly fill out the data I need?