Extend the IDEA Android designer plugin

I'm developing a custom layout class for Android. This class is already working; I can specify a layout in an Android xml file and it shows up nicely in the Designer preview.

Now, I like to be able to edit this layout using the IDEA Android Designer. What are my options to do so? If I read the plugin documentation correctly I can write a complete new designer plugin but I like to use all the existing Android infrastructure. My preferred option would be to write a separate plugin that just extend the functionality of the original Android plugin. Is that possible? or do I have to create my own modified Android plugin? (what I would like to avoid)

I'm currently looking at the code at: git://git.jetbrains.org/idea/android.git Is that the correct code? Can anybody point me to the part where components are loaded into the widget palette? Maybe its a good start to make may layout class show up in this palette?