As for rules, I'm sure lots have been made up. Dave Taylor even has his Adeptus Mechanicus "counts as" Lost and the Damned army. But that won't really help will it... sorry.
As for fluff, the Lexicanum is pretty good, as is Wiki. Also, if you go on the Specialist Games site, and go to the Inquisitor section under the "Articles" section, there are a couple Mechanicus rules examples as well as a bunch of fluff.
http://www.specialist-games.com/inquisitor/articles.asp
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Lord of Fluff and Blood Angels
Herald of Nurgle
"I wield my power with the Emperor's Authority. Those who would say that I am 'radical' merely have minds too small and impotent to realize all the weapons at their disposal. Do not question my methods on account of these so-called 'Puritans'."
-Inquisitor Mathias Rosenadel