amibcp 4.53 works on our BIOS.
I did find a flash tool that successfully flashed.
If you use fpt from the flash toolkit (FTK), you can flash it manually.
FTK google translate
Make sure the bios you flash has had the capsule stripped (the ASUS site has the capsule). I don't think fpt can handle it being there.
I did that by simply backing up my existing BIOS, as that gives you a clean file to start with.
Backing up:
fpt -d backup.rom -BIOS
If you don't specify -BIOS, it will fail to backup, since we can't dump or rewrite the intel ME firmware. Setting Me FW Image Re-Flash to enabled might allow this (under PCH-FW Configuration).
To flash the BIOS,
fpt -f flash.rom -BIOS
POWER OFF after you flash. It won't take effect until you do (not even a restart) due to the EFI quick boot feature keeping the old BIOS in RAM.
I was unable to get the chipset option to show up, however. I tried every option, but no dice so far. Everything else seems to show. I've attached my modded BIOS, where I exposed most of the helpful options in advanced.
Anyone have ideas on how to get chipset to show up?