Please, do not use compression fittings. Compressions fittings are not intended to hold up under high pressure and could blow off when you are really slamming the brakes (and need them most).
I know there are rednecks all over the internet that will tell you that compression fittings are okay, and nobody they know has ever had a problem, etc... but it's not worth the risk to save a little bit of time. People can die from hack jobs on brakes.
Use flares and unions, or better yet, replace the whole line since it's probably pretty badly rusted in several places. And bleeding the brakes isn't bad, just time consuming.
