Hard Brake Line

Hi, need some help on how best to change the OSF hard brake line to master cylinder. The old line has been rounded off so need to replace with new line but wanting to know if this can be done with engine in the car as the line runs at the back of the engine. Any help most appreciated and whether the line can be replaced with engine in the car!

It can be done, it's bit fiddly as you'll be lying under the car, but doable. I would start at the wheel end, put the fitting and flare first, then you can cut any excess and flare at the MC end when you aren't lying on the ground.