I've just finished installing Sierra on a Sandisk Extreme Flash Drive (see attached file) and had a few hiccups along the way.
I had to use Clover r3590 along with a newer version of CLOVERX64.efi (not sure if this is needed along with the newer Clover version). With the new Clover version I was able to reach the installer screen.
I also had to remove USBInjectAll.kext from my Kexts -> Other folder, before the installer would load. So I only had FakeSMC.kext (Kozlek branch) and IntelMausiEthernet.kext in my Kexts folder. I also removed all SSDTs from ACPI -> patched. Things went smoothly from this point on-wards, though I only had keyboard control during the installation.
Once in Sierra, I wasn't able to install the latest Nvidia Graphics Beta drivers - I got a message saying they weren't compatible with my OS version.
Edit: For brevity & removed links