Hi Mo-6420, thanks for your guide to install mac on E6420. I have E6420 with Intel and having trouble installing Catalina.
I have partitioned my (only one HDD) to GUID with 4 partitions (two APFS and two FAT). Before installing mac, I checked the SIP thru installation disk terminal (by command csrutil status) and it is disabled. Installing Catalina from USB does not have any issue/error, unless at the end it cannot set the startup disk. Also after Installation and initial setup complete, the clover installation also fails. I can run the mac only by using the USB installer disc.
I copied the your OC and EFI folder to one of the FAT partition and set the BIOS with new UFI boot entry as per your instruction. Booting thru OC the mac is stuck at apple logo.
I reinstalled the mac three times (including one time by re-partition/erase the disk) but the same result. Also I have observed that after installation, the mac partition is read only (that i have to make write enable by commands spctl --master-disable, mount -uw / , killall Finder).
I hope you can help to up and running mac on E6420.