I can only seem to find guides on how to replace existing microcode and vbioses, or add new EFI modules.
I already have the new microcode, vbios, and GOP, just need to know how to add them using MMTool

EDIT by Fernando: Thread title shortened (added modules are natively not present)

Wot NEW modules u want to add to a bios?
MMtool can insert anything as long as the volume as space for it...but its not such plain easy as u may think, doesnt work just inserting stuff in it.

BE more specific on ur hw and intentions

I want to try and add support for carrizo APUs to my motherboard, i already have the microcode and vbios from another motherboard.
Just want to add them in.

Good for u...already have mcodes and vbios modules, so go ahead with MMtool and u'll get a dead "Unknown model"motherboard.
Wot part of the "Be more specific on ur Hardware" didn't u understood?
This is not for users u do not have some experience and knowledge on this subjects.
Post a request with the correct identification of ur motherboard, bios version, provided links for original bios files and maybe someone can help u.
BIOS Modding Requests

Yeah, kinda had a feeling you were going to say that after i typed the response.

I have a GA-F2A88X-UP4, and i want to add support for the carrizo based A8-7680.
I already added the microcode, GOP, and VBIOS onto the motherboard bios, but i can't boot after flashing