Is it possible to replace the power pressure line without dropping the engine down.

Possible? Probably.
Easier? Probably not.
Lowering the rear of the subframe is very easy when the car is on a lift.
I wouldn't want to do it with floor jacks and jack stands.
But thats cause i'm spoiled;)

do you just have to loosen the two back end boltsof the frame to do this? thanks