you need to do it from inside the car... the easiest is the passengers side as you don't have the fuse box in the way. however it's still a nasty fiddly job and you have to ensure that the pipe hasn't shrunk or the groomer/ spout hasn't cranked.
for best access its advisable to remove the front seat and all the side panels & glove box around the dash.
is the least you'll need a torch and lost of patience.