If your lines are new and have not been filled with fluid then "bench bleeding" is irrelevant. The amount of air in the MC is nothing compared to the air in the lines. If the lines have been filled (at some point) with fluid then try this: Connect the lines to the MC. Crack open the lines just like a bleeder screw while pressing down on the brake peddle. Close the connection before releasing the peddle. This will force most of the air out of the connection instead of forcing it all the way through the lines. You may still need to bleed the lines if the peddle is spongy.
