The co-ordinates will bring you from the parking area to the mausoleum door (Rusty Door). Find the stone plaque left of the door and count the occurrences of the letter X on this sign. Let that be X ;-)
The cache co-ordinates are:
N 53° 11.90(X+4)
W 008° 54.(X+2)2(X+3)
Enjoy!