It seems some of the problems I had installing Debian to the 2006 MacBook were due to the drive I was using for the installer and also the MacBook itself since my MacBook is now non-functional. Make sure to use a USB flash drive and if you have issues then try using another one as not all flash drives are bootable on a Mac. The Debian installer works correctly, but needs one slight modification to boot on a MacBook which I will explain shortly.
The Debian installer by default does not have the necessary drivers to allow for installation using WiFi, so connect your MacBook directly to your router using an Ethernet cable. You will also need to use an USB mouse since the trackpad is not functional in the current installer. If you don't have a USB mouse, then you will use the arrow keys, Tab, Return, Esc, and Space keys to navigate the installer.
If you are going to dual boot OSX and Linux, then make sure to shrink your Apple partition using the Apple tools before attempting to install Linux.
If you want to use the built-in iSight camera, then you need to retrieve the camera firmware from your current OSX installation and save it somewhere else if you are going to use the whole drive for Linux. The camera firmware should be located on your OSX drive here:
/System/Library/Extensions/IOUSBFamily.kext/Contents/PlugIns/AppleUSBVideoSupport.kext/Contents/MacOS/AppleUSBVideoSupport
To create a bootable 32bit Debian 10 (aka Buster) USB installer you need to download the RC2 (Release Candidate) installer from here. In a few weeks the official installer for Debian 10 Buster will be released and can be downloaded from here (select the i386 link under "Small CDs or USB sticks").
Create a bootable USB installer by using Etcher (Mac/Windows/Linux).
In order to boot this installer on a Mac you must rename the bootloader so that the Apple firmware will recognize it. After creating the bootable Debian USB installer you must first mount the second partition of the installer and rename the bootloader located on the second partition at /EFI/boot/bootia32.efi to /EFI/boot/boot.efi. The Apple firmware will only recognize an unblessed bootloader located and named "/boot/boot.efi". Unfortunately OSX/macOS is unable to mount this partition read/write so it must be done using Linux (you can boot a Linux LiveCD/USB for this step). It might be possible to do this with Windows, but I haven't tried it as I don't use Windows.
Option Boot the modified USB installer and select the orange icon labeled "EFI". When asked about installing non-free drivers, just select "No".
When you get to the step for partitioning the drive, select to use the whole drive and all files in one partition. If you are planning to dual boot, then select to use the free space.
When asked to create a root password, just continue past without a password so the "root" user account is locked like it is with OSX. There is absolutely no need to have a separate root account.
At the software selection stage, I would recommend selecting either "Mate" or "KDE" for the Desktop Environment (aka GUI interface) since they both provide a Touchpad configuration utility whereas LXDE and XFCE don't have a touchpad GUI interface built in. I would also suggest making sure the "Print Server", "Laptop", and "Debian Desktop Environment" are all selected as well.
When the installation process finishes and before restarting the laptop, I would suggest you rename the bootloader by moving to Virtual Terminal #2 by pressing and holding the Control + Alt keys followed by pressing the Fn + F2 keys (while still holding the Ctrl + Alt keys). You should be presented with a black terminal screen where you are asked to press "Enter" or "Return" to enter it.
In Virtual Terminal #2, execute the following commands to rename the bootloader:
cp -vr /target/boot/efi/EFI/debian /target/boot/efi/EFI/boot
cp -v /target/boot/efi/EFI/boot/bootia32.efi /target/boot/efi/EFI/boot/boot.efi
Now go back to Virtual Terminal #5 where the GUI installer is located (press and hold Ctrl + Alt, followed by pressing Fn + F5 ) and allow the installer to finish and reboot the laptop.
While running Debian on the 2006 Macbook, I had trouble performing a warm reboot. The only way I could perform a warm reboot was by sitting at the GRUB bootloader menu for 2-5 minutes by pressing the down arrow, followed by the up arrow to stop the automatic boot timer. After 2 to 5 minutes I would then press "Return" to select the first option. I'm assuming the issue was with my MacBook as I've never seen this behavior on any other Mac.
I'll post some post-install instructions for installing the WiFi drivers and a few other customizations you may need.