have been using this technique for that last year...I get great results and don't have to fight with any jigs. use drill press to drill for the insert and as a guide...but...DO NOT TURN IT ON WHEN INSTALLING THE INSERTS!!! I will let the pics tell the story... BTW, I use a 10mm brad point drill bit to drill for the inserts. You can get the inserts and that special insert tool from McMaster-Carr... I apply just enough downward pressure on the drill press...you will feel the insert pulling as you rotate the chuck by hand with the aid of the 1/4" rod. Once I have them all in, I use some thin superglue to wick between the wood and the insert...it holds them in place. I hope this helps out...I usually try to do this before I glue the fingerboard on...but have done quite a few retro-fits...I use a radius sanding block to hold the neck in place while drilling and while installing the inserts.