The attached (unsupported) third party utility should do what you want i.e. unzip the files and place the phoneon.lnk file in \Application\Startup and the EXE file in \Application. Whenever the device is rebooted, the phone will be switched on if it was off before the boot occured.

I'm not sure that using registry values would be the best way to do this, if it is all possible (I did a few experiments on my ES400 today but couldn't get it to work in a reliable manner). I would recommend to write either a script or a simple application using the Motorola EMDK that powers on the radios, then place this in the \Application partition together with a .run file in \Application\Startup. The .run file will ensure your script/app will be executed every time the device boots.