In my experience they work better with the cross over cable longer than shorter.

Set up the shoes to be parallel to rims and roughly half way extended in the clamp. Use a Third Hand to clamp the calipers, adjust to tighten cable play at the yoke. Remove Third Hand, squeeze brakes a number of times firmly to stretch cables; toe in pads slightly at front (grab arm by shoe with small adjustable wrench tightened to arm above shoe post and turn gently); readjust/tighten play with Third Hand at one end of the cross over cable. Fine tune with adjusters on levers.

Squeal away!

Oh, horizontal and shoe surface square to the rims.