Thanks to Eva for this Frugal Baby Tip!
Basically they look like this :
== ------===== <--- these are the ties
..... ------ <--- this part is longer in reality!
The scarf-like part below the ties makes about 50 % of the entire length. You fold the diaper in the middle so that the ties are at the end of the diaper and the thin scarf is on top of the wider part. Then you put the doubler/liner on the diaper, place the baby on the diaper, pull the wide part over babys tummy and hold with on hand, put the scarf part between baby's legs, cross the ties first behind baby's back, then bring them in front and tie. I hope this is clear enough... It may sound like the procedure is awfully complicated, but in fact it is easy once you get the knack. Provided the baby is not too wriggly!
Making this kind of diaper yourself may be difficult unless you have a professional knitting machine! They are made of a very thin cotton yarn in a rib-like style (sorry, my English leaves me here) to make them elastic. I have never tried to knit such a diaper myself, but it would certainly be possible. But a lot of work!
I did not follow the original thread, but sure you could sew fitted diapers and instead of using Velcro, pins or snaps, add ties to the front flaps. Should be no problem to tie them then. Instead of folding the ties behind the back you would then need to cross them over the tummy first, then at the back again. BUT make sure that the diaper needs to be at least waist-high, better add an additional inch...