How to customize the skeleton generators?

Hi Yii folks,

we want to customize the skeleton generator of YII to use YAML as the default layout and CSS template. It seems, that the WebappCommand that creates the skeleton mainly copies some files from framework/cli/views into the new application and does some config. It would be easy to exchange the sources in this folder, but its not a good idea because its in the framework path. How would you extend YII to overload the default behavior and create custom skeletons ?

Kind regards,