I'm following your posts on this. Most of what I'm reading, requires an edit of the AMI bios modules in order to fully unlock the bios for uefi. Doesn't sound like something I want to try right now. I was hoping someone already made the mods to the bios and could publish it.
If the posts from that one dude who stated he had it all working have been removed from the thread, then chances are it was bunk and don't get your hopes up.
My attempt at hacking my n56vz got to the same point it sounds like you're at, I can boot as long as the usb drive is plugged in. I tried a few things from multibeast (one at a time,) and few on them cause KP's and few are okay to load.
When you first booted from the usb drive, did you get a black screen show up really fast that read something about the nvidia card or driver? I saw it but it was too fast for me to get the full text. Anyway.... I'm trying some things and I'll keep you informed. This laptop should make an awesome hackMBP.