Hi
I use the double back method. I do not ream pearls out to do it. (I find that a real pain) Instead, I have several weights or thicknesses of thread. when in doubt, I test the proper size thread by putting the pearl over a threaded needle, then doubling back the same way. If the thread will fit through twice, I use it. Generally, for a .8 hole medium thread (or 20lb PowerPro) works fine. I have forgotten the proper size of silk, maybe a EE? Another test is to make a knot in the thread and put on a pearl. If the thread is too small, the pearl will slip right over the knot. In this case move up a size of thread --or make a double knot.
Don't try to absorb everything before you even begin. Just look up the one part you need to move along, then another part. Also that Henrietta Virchek book can teach anyone to knot in the way that comes easiest. I only use the 2 thread method precisely because you can get the knot snuggled really tight up against the pearl. Using a single thread with an awl to move the knot in place requires great care, because if the instrument slips out before the knot is tight against a pearl, it is difficult to impossible to loosen it up with the awl (or other tool) and get it moved. I tend to fray the knot when I try, so I quit that method years ago.
So start by attaching the clasp, then do the knotting, then attach the other side of the clasp trim the excess thread and you are done.
This is a question for everyone: Have any of you used the new style clam shell shaped like a V? It has a hole in the bottom for passing the thread through to the knot. The V is then squeezed shut and a ring passed through the holes in the top and through the clasp. I forget what you call those doubled rings like car keychain rings, but they would be very strong.