Install Alpha Manager plugin to TinyMCE

After installing the add-on will be available from the standard "Insert/Edit image" dialog.

TinyMCE AlphaManager screenshot
  1. Unpack archived files directly to tinymce/plugins.
  2. Turn on the plugin in initialization script:
    plugins: 'alphamanager'
  3. Now you can use your installed plugins. Do not forget to sure that browser cache was cleared.