update: Nick has posted a little bit on information on the HaloDev site about the chapter introducing Prometheus.
"For a very long time now we’ve been working with Stephen Cawood, author of O'Reilly’s ‘Halo 2 Hacks’, on his new book ‘The Black Art of Halo Mods’. The book is focused on creating new maps with the H.E.K. JamesD and Grenadiac, along side many other modders, spent an awful lot of time helping out with the H.E.K. section of the book." full article