Tested to verify as of: 6.0.12 with 6.0.12 Plugins SDK, Trunk (Rev. 111409) with Trunk Plugins (Rev. 111409)
A customer would like the ability to override liferay-portlet.xml using the Hook option for Plugins SDK. Currently after some investigation, it seems the only way to override the XML file is to:
1. Create a liferay-portlet-ext.xml
2. Create an ext plugin
For custom development, customers would like to be able to use hooks instead of the ext plugin.