This article is from the Hanggliding and Paragliding FAQ, by Joao Geada with numerous contributions by others.
Set the glider up and place on saw-horses at a normal flying angle of
attack. The base tube should be just off the floor. Mark the location
of the base tube on the floor with chalk. Lengthen the front wires the
required amount listed above. Use the shorter measurement for
long-armed pilots and the longer one for short-armed pilots. The
cables may be easily lengthened by adding cable segments (with
thimbles) to the existing cables. Use a known good Nico-Press tool to
swedge the Nico sleeves. Now shorten the rear wires enough to tension
the lower wires to the same extent they were before modificaton. This
may be done by carefully slicing open the Nico sleeves with a Dremel
tool with an abrasive cut-off wheel and then spreading them open. Now
install new Nicos, pull cable through the thimbles until tight and
crimp the Nicos. Use Dremel to cut off excess cable.