I have a successful installation of El Capitan 10.11.6 on a MacBook 4,1 using method 3 with variations.
Keeping it short, what I ended up doing was:
- Installing EC and applying all updates to a USB-attached SSD on a MacBook Pro 3,1 already running EC
- Putting all the proper kexts, as discussed elsewhere in this thread, into the Extensions folder
- Replacing the “Apple_iSight.kext” with one from a Lion installation into the Extensions folder (see below)
- Performing all the proper blessings and permissions changes
- Putting the USB-attached SSD with EC into one of the MacBook 4,1 USB ports
- Creating a USB flash rEFInd stick and inserting it into the MacBook 4,1
- Starting up the MacBook 4,1 and setting SIP to “off” in the rEFInd bootloader
- Selecting the EC disk and starting it up
- Manually installing and configuring rEFInd to the EFI partition on the MacBook 4,1 making sure that I setup the SIP switch to OFF (and only off)
- Rebooted into El Capitan without the USB rEFInd stick attached
The iSight camera didn’t work (and the light was stuck “on”) without the Lion kext and I actually tried that last, re-blessing and “permissioning” again. I was surprised that worked.
The graphics issues are there but tolerable. The screen brightness is stuck at a reasonable level. I installed the free “QuickShade” app via the App Store which allows some control over brightness.
The USB ports, Bluetooth, audio, wifi all work. No worries anymore about Apple updates mucking it all up as there won't be any.
It wasn't as easy as it sounds but it would be if I had to do it again!