Robert,
maybe this piece of code coul'd do the job in init() function :
for ( var i= 0; i < this.configData.widgets.length; i++){
var mainConfigWidget:Object = this.configData.widgets;
var swfName:String = "/"+this.className+".swf";
if (mainConfigWidget.url) {
var widgetUrl:String = mainConfigWidget.url as String;
if (widgetUrl.indexOf(swfName)>=0){
WIDGET_URL = widgetUrl.substring(0,widgetUrl.length-swfName.length) + "/assets/images/";
}
}
}