Prepare USB Drive

Before start

Prior to installing OS X, it is a good idea to create an OEM recovery USB from Windows. If anything goes wrong and you want/need to get back to Windows, you can restore it via the USB. Use the utility provided by HP to accomplish this.

Setup the USB drive

You must determine what the disk identifier is. With the USB plugged in to the computer, open a terminal and digit:

diskutil list 

The output should look like this:

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.1 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS 10.10.x                 80.0 GB    disk0s2
   3:                  Apple_HFS 10.11.gm1               80.0 GB    disk0s3
   4:       Microsoft Basic Data Win10_TP                79.4 GB    disk0s4
   5:                  Apple_HFS 10.10.test              80.0 GB    disk0s5
[B]/dev/disk1 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                                                   *8.0 GB     disk1[/B]

So I can see that the USB is at /dev/disk1. Be careful with diskutil as you can lose data without a mechanism for recovery if you repartition the wrong disk.

Now you can format the USB drive with:

# repartition /dev/disk1 GPT, one partition
# EFI will be created automatically
# second partition, "install_osx", HFS+J, remainder
diskutil partitionDisk /dev/disk1 1 GPT HFS+J "install_osx" R

The output of the operation looks like:

Started partitioning on disk1
Unmounting disk
Creating the partition map
Waiting for the disks to reappear
Formatting disk1s2 as Mac OS Extended (Journaled) with name install_osx
Initialized /dev/rdisk1s2 as a 7 GB case-insensitive HFS Plus volume with a 8192k journal
Mounting disk
Finished partitioning on disk1
/dev/disk1 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *8.0 GB     disk1
   1:                        EFI EFI                     209.7 MB   disk1s1
   2:                  Apple_HFS install_osx             7.7 GB     disk1s2

Installing Clover Boot Loader to USB drive

Download https://github.com/RehabMan/Clover and run the Clover Installer package:

• select the target of the install to install_osx using Change Install Location

• select Customize

• check Install for UEFI booting only, Install Clover in the ESP will automatically select

• check BGM from Themes

• check OsxAptioFixDrv-64 from Drivers64UEFI

After making your selections you can continue to Install the Clover Boot Loader to your USB. Finally, we need one EFI driver not included in the Clover installer, HFSPlus.efi. It can be downloaded from here, then copy it to /EFI/Clover/drivers64UEFI

Please, DO NOT forget HFSPlus.efi. Without it, you won't see any HFS+ partitions, including the HFS+ partition that the OS X installer is on.

If you're installing High Sierra (10.13) to an SSD, keep in mind that the file system will be APFS, which requires apfs.efi in drivers64UEFI. Without apfs.efi in drivers64UEFI, Clover will not recognise APFS boot volumes. You can find apfs.efi at /usr/standalone/i386/apfs.efi inside of /Applications/Install macOS High Sierra.app/Contents/SharedSupport/BaseSystem.dmg

Now you have the Clover bootloader on the USB, the resulting drivers64UEFI should look something like this: