Search for "pierece point build along" in the bowyers bench forum and you will catch a couple glimpes of how it is done. I use a finger joint router bit for this.
The late Jerry Pierce, from central IL, came up with this great idea as he was gluing together extra scraps of hardwood to use in a bow riser. Seeing the interesting results the jointery made, his experimentation continued and his ultimate results were outstanding.
This process takes some time, but is worth the effort.