This is a very hard way. you need to do reverse engineering of all motorola bootloaders

For more information see here:

Security in Motorola Droid family

Boot chain

Disassembling

Here you can find useful things for the IDA Pro for droid reverse engineering: http://gitorious.org/droid/ida

Here you can find latest IDA databases of thease bootloaders http://gitorious.org/droid/reversed