So, i solved it with my own dependency loading, like this:

        (function () {
            var dependencies = ['/tiny_mce_popup.js', '/utils/form_utils.js'];
            var left = dependencies.length;
            var tinymce = ((!window.frameElement && window.dialogArguments) || opener || parent || top).tinymce;
            for (var i = 0; i < dependencies.length; ++i) {
                var dependency = dependencies[i];
                var script = document.createElement('script');
                script.src = tinymce.baseURL + dependency;
                script.onload = function () {
                    console.log(script.src,'loaded',left)
                    if (--left == 0) {
                        tinyMCEPopup.onInit.add(SimpleImage.init, SimpleImage);
                    }
                }
                document.head.appendChild(script);
            }
        })();

SimpleImage is my "popup controller".