I've made several pairs of Huaraches, Vibram 4mm cherry material makes a brilliant feeling sole, thicker can be nicer on rougher ground.
For me getting the ties right was the hard bit, lots of experiments with different methods to find what suited me, think the practice and experimentation helped. I found latigo leather more comfortable than the round shoe laces Invisible shoes use, for the latigo laces I made a leather pad (see avatar) to go under the knot as was breaking the skin on runs above 5-6 miles. Since then have tried Barefoot Ted's elasticated leather laces and they are my favourite now, giving the most comfortable secure fit, check out the luna sandals website.
Sqeakz - nice quote, I agree, in proper barefoot intervals dont even notice small stones when form is good, when its not so good feel the tiniest piece of grit