If you're using my 7510 bootpack from the guide, it's already included under /EFI/Boot/DVMT
Modify grub.cfg and change
setup_var 0x432 0x3
to
setup_var 0x432 0x4
Save and reboot
Go to the BIOS
Create a new boot option, call it DVMT or whatever you like
Point it to /EFI/Boot/DVMT/Bootx64.efi
Save and reboot, press F12
Select the new boot option DVMT or whatever you assign it
At the grub shell, select Option 1 for "#1 iGPU-only configuration. No dGPU. "
Or you could download modGRUBShell.efi, add it to drivers folder and enable it in the Config file
At bootup, press spacebar to review the boot option. Select it to boot to the Grub Shell and run the command
setup_var 0x432 0x4