Start with the cut at the back taper. Find the spot where the rear taper ends, measure out another six inches and make your cut there. Soak about 1 1/2" of the cut ends in acetone for about a half hour to soften up the coating for removal. Once removed, double the core back until it forms a loop of about 5/8" long. Using 20# dacron (not mono), nailknot the loop with the knot abutting the end of the coating. Trim off the tag ends of the core and dacron then whip finish with thread about 1/4" onto the loop and about 3/8" back over the fly line.
For glue, I've been using Beacon Fabri-Tac available from Michaels craft stores or from fabric stores. It's an acetone based glue not water based so it won't come apart when wet and the acetone bites into the flyline coating. Thin a small dob of it with a bit of acetone so it is runny, then coat the loop. It dries in about 1/2 hour so repeat the process for a second coat. When it is almost dry, roll it between your thumb and forefinger so as to produce the smoothest finish you can get. This produces a very flexible, strong, smooth, low-hinge, low-snag loop.
This rig has a definite sweet spot so it's best to test drive it before making the tip cut. It isn't completely necessary to make this cut however, it would result in the running line loop being down around your feet on the cast. I prefer the loop at the fingers of my top hand. Having the all of the taper in the guides helps with the rod load. These loops shoot through the guides cleanly with no fuss so there's no need to set this rig up with the loops beyond the guides and I think it would prove counter-productive to do so.
Make a temporary loop at the original front of the fly line and connect it to the running line. Set up your usual leader rig, splitshot, fly, etc. and go casting to determine the best head length for your rod, then mark that spot at your fingers where you grasp it with your top hand on the cast. Cut and loop at this spot. Finish up by making loops for the leftover tip so you can easily restore the line to its original configuration, should you wish to use it that way.
In my case, the 10' off the front end was perfect (dumb luck -- I cut before testing) so it also gives me a good polyleader line used the right way around with no tip section.
Since the head it so short, it takes a bit of a casting adjustment. A gentle sweep makes the D-Loop then, as the leader straightens out on the anchor, just make a quick snap with your bottom hand as if you're trying to cast with just the tip of the rod. Make a high, hard stop with the rod butt in the belly and keep your top arm bent, with the elbow by your side. Then admire the line singing out . . . .
Unlike the comments on singles and shot made by a couple of the PNW boys, this rig has no trouble lifting sunk splitshot on the single or double. If you allow the shot to sink too much, the worst that seems to happen -- you get a shower from the spray produced as the powerful, energized head rips the rig from the water.