I essentially, do the same way as yew archer (can be seen in the pictures I posted), except I use a tennon saw to cut the slots and find the wedge can be cut to fit nice.
How far down I taper the shafts depends on what sort of weight I want and where the balance point needs to be.
I have 2 long blocks with strips of sanding belt fixed to them. the blocks are then fixed to a board, 1/2" apart at one end, 3/8" at the other. then hold an over length arrow shaft in a pistol drill and run the shaft at slow speed between the blocks, from wide end end to narrow. I can adjust the taper between the blocks to suit what I need and how long the taper needs to be. used belts are ok but they get hot and don't cut so well.
I don't know if you can get them there but I use carburundum coated foam blocks for finishing off the sanding. sort of wrap it around the shaft and sand lengthways.