For $29/mo, we provide access to advanced level technicians who will answer your questions on any Macbook board related matter to the best of their knowledge promptly & walk you through how to solve your problem so you can deliver a working board to your customer.
They aren't hard to find, just need to get to the SPI rom and change some values. You can either de-solder the rom and connect it to a SPI Writer or get a breakout cable for the JTAG connector (which is my preferred method when I need to do anything with the SPI rom). You don't even need to disassemble the device when using the JTAG.
Look for this online as its fairly simple and there are lots of tutorials out there
Keep in mind that doing this for customers is risky as they're often stolen devices, something you don't want to work with.