The spokes do stay in the hole in the same way as standard spokes.
The tool I designed and had made, but I was very lucky the engineer completed it.
There is an improved version that has been with the engineer for four years now, it's nearly complete, but I can't get him to do the final little bit.
It really comes into its own when experimenting with different lacing patterns, and when you're not quite sure how long the spokes should be; if you've got it wrong, just cut another set.
I'm sure this would make a valuable tool if it were produced, but I don't have the resourses, and I'd probably get ripped-off, as usual.