I can see where a dealer would lift the body off of the frame for those line changes. I placed a small scissor jack between the frame and body and lifted the body slightly. If you look at the body mount bushes, they are made for this sort of movement. Like many things, this is a situation where subtlety is key. Lift it only what you need and then sneak the line or lines out. Too much movement will probably wreck something.
If you are telling me you have replaced your lines by jacking the body slightly then i would be very very interested to hear more as this would be a great help to hear how you did it.
It would also mean that i could get the pipe and do it my self. I guess the exhaust would have to come off?