It's very simple to replace the brake line. Cover everything even after evacuating the line. That fluid is deadly to paint. Most reputable bike shops will have brake lines and different angle banjo fittings. Measure how much shorter your line should be from one banjo fitting to the other. A piece of thin wire works nicely for this. Either note the angles of the banjo fittings or bring the old line with you. Get new copper crush washers. Absolutely not worth it to re-use the old ones.
Once installed, I would highly recommend a vacuum pump to help get the majority of air out of the line. It will still take quite a bit of time to remove it all. Last time I replaced my front line, it took me 3 and half bottles of fluid and about 2 friggin hours. Conversely, when I changed the front brake line on my wife's T100, it took about a half bottle and about 30 minutes. Go figure....
