I installed a 2" longer brake line a couple days ago. The trick for me was to do it when I had the rad off for a valve check, it made getting at the 10mm? bolt on the hard line compression fitting a piece of cake. I attached the line and filled the MC with fluid and gently pulled the lever just a little bit so I could see micro sized air bubble rising. I had to leave it overnight for gravity to do its job and fully fill the line then in the morning I bleed the brakes as usual, I used a 1 way valve that I bought at cycle gear for 15.00.
Rick I sent you a PM