Post Installation
Install Clover UEFI as described in the guide linked by the previous section (post #2). After installing Clover, and configuring it correctly (config.plist, kexts, etc, just as you did for USB) you should be able to boot from the HDD/SSD. The configuration at this point should be exactly the same as USB. Don't forget both HFSPlus.efi and HPFanReset.efi.
But there are still many issues and devices that won't work correctly. For that, we need to implement power management, configure ACPI, provide a proper config.plist, and install the kexts that are required.
Since you have RealtekRTL8111.kext/IntelMausiEthernet.kext already injected by Clover, you should have internet access simply by using an Ethernet cable to your router. Plug it in and make sure you have internet access before continuing. Or if you're using WiFi, you can connect to your WiFi router before continuing.
Installation of the tools and patching is easy provided the scripts and tools at the ProBook repository:
https://github.com/RehabMan/HP-ProBook-4x30s-DSDT-Patch