I just figured out how to do this on Friday for my Wife's 2010 Macbook7,1.
You are correct that this is an issue with the graphics drivers.
A bug in Apple's EFI leads to the graphics card not being initialized correctly and subsequent loading of the proprietary Nvidia drivers fails.
This bug doesn't effect the Nouveau drivers.
This presents three different ways to solve your problem which I enumerate below.

## Patch the Bootloader

It's possible to get the drivers working in EFI mode by having the bootloader initialize the graphics card instead.
This solution is described in the Debian Wiki [here][1] under the section _Black screen fix (EFI mode)_.
If you are unable to boot into your system at all like I was, you will need to boot the installation media, select _Try elementary OS_, mount your installed partitions, and chroot into the installation before following these instructions.
The chroot process is described in the Debian Wiki [here][2].

## Legacy BIOS

You can install elementary OS in legacy BIOS mode in which case the graphics drivers are initialized correctly.

## Nouveau

Removing the proprietary Nvidia drivers and using the Nouveau drivers will boot and function but this is not ideal.
My wife's Macbook experiences frequent hangs and complete crashes when using this particular Macbook with the Nouveau drivers, particularly under X11.
I can deterministically crash elementaryOS by opening GitHub's homepage in Epiphany when using the Nouveau drivers because of the 3D acceleration.
The laptop also runs much hotter than it does when using the proprietary drivers.

## See also

I also recommend looking into [mbpfan][3] and [TLP][4] to get the most out of your Macbook.


  [1]: https://wiki.debian.org/InstallingDebianOn/Apple/MacBookPro/7-1#GPU_.2F_Nvidia_Geforce_320M
  [2]: https://wiki.debian.org/RescueLive
  [3]: https://ineed.coffee/project/mbpfan.html
  [4]: https://linrunner.de/tlp/