'.....how do you tie the thong of.........' could relate to anythingg similar, such as tent ropes or leather boot laces that we used on our old leather soled (up to the mid to late 60's or so and rubber soled ankle high boots (up to the 80's or so). The answer was that so long as the leather laces were done up tight, crossways, that was all that mattered so far as the room Corporal and platoon Sergeant were concerned. Whether you did it with a knot at one end and threaded crossways all the way up or ended up with two end at the top didn't matter at all. (Some never even used the top lace hole to make squatting more comfortable). The knot was academic - just so long as it didn't come undone during drill periods!

Exactly the same as your leather rifle sling, although we always used webbing in my short time in the Army! Just thread the leather lace through and tie the knot, securing the both parts together making sure that a) it stayed tight and b) you could get it apart when you needed to.

Just my 2c's worth looking from the bleedin' obvious angle