Simply get a long piece of bare copper wire (I use the ground wire from Romex house wiring.) wrap several times around the threads of each plug, bend a loop in the free end and insert it into a plug hole. BUT really, why bother? With the key off, Jump the starter solenoid from the battery side to the thin yellow wire. The engine will crank without spark.
The carbs do not need to be mounted on the engine. Since each cylinder goes to atmospheric pressure as the ports open, it simply doesn't matter if the carbs are open or closed, mounted or not. Sure, the engine will crank slightly slower with the carbs mounted and closed but again practically speaking it simply doesn't matter.
For each cylinder, crank the engine at least four turns or until the compression stops rising.
