I have used compression fittings for a temp brake line fix. I'm pretty sure that they are specifically not "legal" to use for a brake line fix. The better alternative is to cut the line at a point with good metal, slip a fitting over the line and flare it. Then add another line by attaching it via fittings.
Its more work, but safer for you, your family, and me.
Current truck: 2002 PSD 4x4, CC, XLT, F350 dually, 4.10 gears. Air bags, 6.0 trans cooler, Fleetrite ELC, ISSPRO gauges (boost, EGT, trans, fuel pressure), PHP Hydra, full EBPV delete (pedestal & outlet), CNC Fab HP & HPX lines, Riff Raff FRX, Riff Raff IC boots, CCV mod w/catchcan, Reese Titan, AIS, ITP pre-pump filter kit, in-tank mods, Redhead steering box.
Old truck: 2000 PSD 4x4, ext cab, XLT, F-350, auto, V-code springs, air bags, coolant filter, 203 thermostat, CCV mod, Fleetrite ELC, DB Alternator, DB high-torque starter, Tru-cool Max-cool trans cooler, B&M trans temp gauge, 47 gallon Titan tank, ITP pre-pump filter kit.