Spread the tarp beneath the boxwood hedge to collect the foliage you cut.
Wrap the rope loosely around the boxwood from the base of the shrub up to the top to create a spiral pattern to follow. Depending on the height of the boxwood, you will probably wrap it around the shrub only two or three times with six to eight inches between each wrap of rope. Stand back and assess the wrapped rope, adjusting it until you like the way it looks.
Cut away foliage between the rope spirals with the topiary shears. Cut slowly and carefully to remove the foliage in to the central stem. If you encounter thick stems, use the pruning clippers to remove them. Stand back often to assess the shape of the boxwood as you work. Continue shaping around the entire shrub until you create a rough spiral shape.
Shake the boxwood hedge gently to remove cut foliage. Assess the shape of the spirals to determine spots where you need to perform more trimming.
Trim carefully around the spirals to make rounded edges. Trim areas you noticed are uneven, if necessary. Continue assessing and trimming until the spiral shape looks satisfactory.
Remove the tarp and discard the trimmings.