This is strange as Recovery Partition patch(for the HFS+ systems) has been available since dosdude1's Sierra patcher and has always worked for me.I guess I was too vague about this, so I guess I’ll need to be more explicit:
- On my MBP4,1 running dosdude1-patched High Sierra, the SSD is partitioned three ways: SL, patched HS, and patched HS installer (the one which would usually be on a USB stick);
- Booting into dosdude1-patched High Sierra installer gets to the installer, but disabling SIP from that terminal window is not permitted (recovery partition boot is required);
- Booting into bog-standard High Sierra installer from USB stick doesn’t work: EFI faults with unsupported system;
- Booting into recovery partition on the dosdude-patched High Sierra is not permitted: unsupported system;
- The dark mode hack link supplied by eyoungren above necessitates disabling SIP first; and
- SIP may only be disabled from booting into a bog-standard recovery partition, which … see #4.
So for now, this remains a chicken-egg question I’ve yet to figure out.
APFS recovery for High Sierra and Mojave can also be patched manually.