Two ways to go about installing that line lock.....The first way is how I did it on my one 70 Charger. The second way I think is better.

1) install it on the front, two real good deep pumps and hit the switch, you should not be rolling.

2) Install it on the rear brakes, hit your switch to lock the solenoid shut and your foot will be applying a stronger pressure on the front brakes than a line lock could. You have foot pressure versus closed pressure. Personally, I should have done it this way but you live and learn.