Editing config.plist on install disk - Opencore

Hi,

I am running through the Opencore Big Sur guide and have been able to get to the stage of first reboot after download/install.

I have problem though which I think is likely related to my config.plist.

How can I access my 'installed' config.plist, not the one on the Opencore USB. I assume that once the installation has started and rebooted the, the config.plist on the USB is not used, and the one on my new EFI partition used instead....or have I misunderstood?

Would I need to mount the volume in Linux or something to read and write this?

edit: I was able to access via Windows