I spent a fair amount of time lining up the nosewheel and rudder to be as straight as possible. In the area under the elevator saddle, I marked the centerline and millimeters on either side. This allowed me to use a long straight edge (1 meter long) and hold it on either side of the rudder to get identical readings. I then used a couple of 1x2 boards and clamped them at both ends, wrapping around the rudder, to keep it in place while I made and fitted the cables. It worked like a charm. Now that the wings are on, working down around the rudder pedals requires circus-level feats of contortion. Aligning the castle nuts on drilled bolts to allow a cotter pin to secure it -- while reaching through in a position I can't even describe -- was the most difficult part of the process, by far. At least it is now in the "completed" column.