1.) Download Yosemite from Mac App Store
2.) formatted your USB Flash Disk or external HDD and rename your USB Flash Disk as "Installer" and format as Mac OS Extended.
3.) Install Yosemite via terminal
sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Installer --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction
3.1) Alternatively you can create your USB Flash Disk or external HDD by using disk utility, see youtube video, https://www.youtube....h?v=C8mdoFuWiJE
this video is not mine!
4.) download Enoch Chameleon bootloader by ErmaC (see Download) Of course you can install Clover bootloader, I've not tested. if you install /Extra/modules files with chameleon
bootloader, then do not to install the FileNVRAM.dylib, otherwise gets "memory allocation error!" and then your system will not boot. and used this bootflag:
kext-dev-mode=1 npci=0x2000 or npci=0x3000 -v , optionally uses the flags from your Mavericks System.
what else to note:
Smbios.plist, DSDT.aml, rom-file, etc. put it in the /Extra/ folder and Modify the org.chameleon.boot.plist
Install FakeSMC.kext, NullpowerManagement.kext, Patched_10.7_AppleRTC.kext and chipset drivers in the S / L / E
Create this folder : System/Library/kernels/ place the amd Yosemite kernel into Kernel folder.
5.) Start the system from USB Flash Disk or external HDD and install Yosemite on your "GUID" formated HDD / Partition.
6.) After installing Yosemite, boot from your second bootable OS X system (possibly from Mavericks or Mountain Lion etc.) and add the Yosemite amd kernel and overwrite the Intel kernel into the folder /System/Library/kernels/
7.) checks your system, what works and what does not work, adjust if necessary
more info follow:
If problems arise with launchpad, with Graphic of the launchpad icons, then used this Launchpad-Fix app, after unzip the file, put the app into the Applications folder and activated the app if necessary. That will fix the problems.
If should problems with the App Store or Safari, then use this FIX:
extracts the AMD-WebKit-Patch.pkg.zip and replace the existing files in /System/Library/Framework/
or invite the complete executable WebKit framework of Duran Keeley
(thanks to Duran Keeley)
If you would like to update to a newer Yosemite, then you should definitely have a second bootable partition. that makes the update easier.
Installing the full update, then start from the second bootable partition. and exchanged the Intel kernel by the amd kernel, then repair the permissions and
renew the cache with Kext-Wizard for Yosemite. then boot from the partition in which you have previously installed the update. and rejoice.