Hi there Larry, I’ve done several period ships and use two methods which depend on access past the standing rigging. The first is to use a fine needle threaded with the lanyard to pass through the deadeye holes, the second is to stiffen the lanyard end with a small drop of super glue and roll it so it becomes a short stiff spiked end (just like a needle!).
I’ve tried the rig which is supposed to make rigging shrouds, ratlines and deadeyes off the boat – but failed miserably with it – I gave it away! Went back to forming all on board, and being patient with the deadeye threading.
Several experts I’ve read make a wooden template for the deadeye distance apart, a downward curved small nail top through a short plank strip, and another small nail curved up at the bottom. Hook the lower deadeye on, then the upper, at least this gives an equal distance between the deadeye rows.
Kimosubby.