Same as if on bench.:-D If you installing new MC, It`s easier on a bench, chucked in vise. If it is an existing MC and you feel their`s air in it, :dontknow: and you want to start from square one. procedure is plug each port on MC, and slowly pump pedal until all bubbles disapear. kinda hard to see while sitting in car. Thats why its best on bench, or if you have a helper. these plugs come with brake bleeding kits or provided with new MC`s. some have tubes that just loop back into resevoir. Then you have to bleed all lines again. fun,fun.