The app MUST be installed on internal storage in order to trigger its execution from the mounting of the SDCARD. It also must be manually run once in order for the auto startup to take effect.
Following a 10 second countdown to allow the cancellation of the ADB from being enabled on the network.
The app executes from /mnt/sdcard (technically Environment.getExternalStorageDirectory().getPath()) the file ./init.rc in superuser mode. So if the file init.rc contained ls -l > dir.lst the output file would be found at /mnt/sdcard/dir.lst