Had the same error as reported here.
I was able to get it to work by replacing VBoxHfs-64.efi with HFSPlus.efi in EFI/CLOVER/DRIVERS64.EFI (*) based on this report:
Motherboard: MSI Z97 PC Mate
GPU: Dual AMD R9-280X Crossfire
I only replaced VBoxHfs-64.efi with HFSPlus.efi and booted with no flags. Installation went fine without any errors.