Got the installer working. Fixed a few bugs including a nasty-to-debug issue where the lang_id was being hardcoded during installation, resulting in strings being inserted with the wrong lang_id causing an infinfinite loop with fetch() throwing a "no strings" error and using template (which calls fetch()) to complain
(function(){tinymce.PluginManager.requireLangPack('example');tinymce.create('tinymce.plugins.ExamplePlugin',{init:function(ed,url){ed.addCommand('mceExample',function(){ed.windowManager.open({file:url+'/dialog.htm',width:320+parseInt(ed.getLang('example.delta_width',0)),height:120+parseInt(ed.getLang('example.delta_height',0)),inline:1},{plugin_url:url,some_custom_arg:'custom arg'});});ed.addButton('example',{title:'example.desc',cmd:'mceExample',image:url+'/img/example.gif'});ed.onNodeChange.add(function(ed,cm,n){cm.setActive('example',n.nodeName=='IMG');});},createControl:function(n,cm){return null;},getInfo:function(){return{longname:'Example plugin',author:'Some author',authorurl:'http://tinymce.moxiecode.com',infourl:'http://wiki.moxiecode.com/index.php/TinyMCE:Plugins/example',version:"1.0"};}});tinymce.PluginManager.add('example',tinymce.plugins.ExamplePlugin);})();