On my 300TE, which has the same armrest, I simply removed the plastic armrest hinge cover and unbolted the 2 bolts holding the armrest to the seatback. I then brought the entire armrest to ReDan upholstery in Newington, and they installed the OE cover I brought them for cheap.
I've been told this is not a DIY job, as it's tough to get the cover on right.
"If everything seems under control, you're simply not going fast enough" --Mario Andretti
1995 E500 street car
1986 Porsche 944 Turbo S track car