This is a quick project that can be done in less than an hour. All you need is a couple of scraps of wood and two bushings, which can be found at almost any hardware store. It is very accurate, given you make the jig precisely.
Dowel Jig simple. Could be improved with bushing inserts and sleeves from lee valley. A brad point drill bit the same size as the holes can be pushed by hand into any hole to accurately mark the center line.