All, the Moana bootloader (or whatever it's called) was never made legally public, so you shouldn't be having this conversation here. Not trying to play forum police, but you know, someone will come along and kill the conversation eventually.
A more constructive conversation would be an overview of what needs to be done to implement a new bootloader, either as a standalone ELF executable, a standalone Forth program, or some combination of the two. If anyone knows the ins and outs of the OS4 boot process, now's the time to chime in.