I did some more digging searching for a real workaround of some kind, not just theory. I found the following: OS X Daily - Got an Older Mac? MLPostFactor Installs OS X 10.8.3 on Old Unsupported Macs. OS X Daily's article links to a series of forum posts at MacRumors - Guide Success! Install 10.8 on old unsupported Mac. It is a very long thread.
This update includes:
Install Os X Mavericks On Unsupported Mac
My suspicion is that the new installer will use it’s own boot.efi / PlatformSupport.plist file(s) preventing you to upgrade using the App Store. My reasoning is that I tried to download the Mavericks Install file from the App Store on the Mac Pro and the App Store prevented the download from happening since the Mac Pro is unsupported. I have a Mac Pro 1,1 that I upgraded to a 2x quad core Intel 5355 chipset. Oem’s script worked like a charm, but - though it doesn’t make to much sense to me, the Mavericks install wouldn’t booth with the stock Nvidia 256mb video card with Netkas’ firmware upgrade to a MacPro 2,1. So it booted into Mavericks fine with the MacPro 1,1 firmware and the stock.
Fixes adfly URL issues- Improves some error messages (makes them more explicit)
Fixes some minor UI issues/glitches
Fixes log files not appearing!
Add some verbosity to the install process (for logs)
Can I Install Mavericks On My Mac
MacPostFactor v2.0
This version is huge! It features many improvements everywhere! Anyway, in this version, you'll find:
Mac Os X Mavericks Iso
Other Features in Previous Versions:
Os X Mavericks Installer App
OS X El Capitan support- Ability to use a smaller Recovery (≈ 600MB instead of 5GB)with no compromises on available features
Bluetooth Audio FIX on 32bit ML Hack- Better MacPostFactor UI and UX
New Preferences Window- New Customise button- Search again for Install OS X _ _ _.app by a click of a button
Nicer interface- Nicer switching animations- Better MacPostFactor App
Better code organization
Snow Leopard Compatibility (BETA)
Contributors now working! Donate to figure on the list!
Ability to change the USB name when erasing it
New feature: 'One click install'
Really fixes Paypal donation link
Fixes USB space check (total space instead of left space)
Fixes ton of other minor bugs
Reduces the energy footprint when creating USB Installers
Better OSXHackers Preview boot logo
Better logs in case of error
OS X Mav+ kernels are now stored online (reduces MacPostFactor's size and allows MLforAll to add a new kernel without updating the MacPostFactor app itself)
Improved the Hacking Process
No more Error Code 3- Use of kernelcache whenever possible
Fixes USB installers not booting
Improved MacPostFactor 'side-apps' (recovery apps)
Better MacPostFactor Services Init- Better OS X Manager with SIP management support
MUCH BETTER 'MacPostFactor OS X Installer” (active progress bar.. support for ML and Mav...)
'About MCPF.app' and 'Dock Glass Effect Manager.app' replaced by 'MacPostFactor Utilities.app' that also adds new tweaks!