Ok, found a diagram thats shows how the line should be hooked up... but I can not for the life of me get to the 2 bolts on the rear of the seat to remove it. What's the trick here? I'm talking the 2 10mm bolts that bolt the seats to the floor in the rear. The rail above them just does not give me any access to them. I have tried of course to move the seat into every position to see if I could find one that gave me more clearance.

Do I have to remove those rails first and again if so, how?

My 87 300D has power/heated seats. So it's not like the diagram in the manual that shows you to remove the 2 bolts on each side. looks nothing like that. The diagram looks to be of a seat with no power anything.