Need Help with Replacing Clutch Master Cylinder

[xxx609]

New user here with a '90 MkIII. Can anyone provide me with any tips for replacing a new clutch master cylinder?
I removed the lower driver's side dash panel and removed the seat to stretch myself out a little easier. One nut to the clutch cylinder is inaccessible!! I noticed that there's a metal bracket that holds the clutch pedal assembly to the metal bottom of the dashboard area - one easily accessible bolt to the bottom of the dash, but I can't determine if the portion of that bracket that mounts to the firewall is spot-welded to the firewall or is only bolted to the firewall with the studs of the new clutch master cyclinder.
Bottom line is - wha's the easier/best way to that inaccessible clutch master cylinder nut. Any help would be greatly appreciated.